Merge pull request #1328 from GriffinRichards/doc-pokeuseitem

Document PokemonUseItemEffects

8 files changed, 475 insertions, 444 deletions

diff --git a/include/constants/item_effects.h b/include/constants/item_effects.h
index f9f329f0f..9a6bcd05e 100644
--- a/include/constants/item_effects.h
+++ b/include/constants/item_effects.h
@@ -31,7 +31,7 @@
 #define ITEM4_EV_HP             0x1
 #define ITEM4_EV_ATK            0x2
 #define ITEM4_HEAL_HP           0x4
-#define ITEM4_HEAL_PP_ALL       0x8
+#define ITEM4_HEAL_PP           0x8
 #define ITEM4_HEAL_PP_ONE       0x10
 #define ITEM4_PP_UP             0x20
 #define ITEM4_REVIVE            0x40
@@ -50,11 +50,15 @@
 #define ITEM5_FRIENDSHIP_ALL    (ITEM5_FRIENDSHIP_LOW | ITEM5_FRIENDSHIP_MID | ITEM5_FRIENDSHIP_HIGH)
 
 // fields 6 and onwards are item-specific arguments
+#define ITEM_EFFECT_ARG_START 6
 
 // Special HP recovery amounts for ITEM4_HEAL_HP
-#define ITEM6_HEAL_FULL   ((u8) -1)
-#define ITEM6_HEAL_HALF   ((u8) -2)
-#define ITEM6_HEAL_LVL_UP ((u8) -3)
+#define ITEM6_HEAL_HP_FULL   ((u8) -1)
+#define ITEM6_HEAL_HP_HALF   ((u8) -2)
+#define ITEM6_HEAL_HP_LVL_UP ((u8) -3)
+
+// Special PP recovery amounts for ITEM4_HEAL_PP
+#define ITEM6_HEAL_PP_FULL   0x7F
 
 // Amount of EV modified by ITEM4_EV_HP, ITEM4_EV_ATK, ITEM5_EV_DEF, ITEM5_EV_SPEED, ITEM5_EV_SPDEF and ITEM5_EV_SPATK
 #define ITEM6_ADD_EV       10
diff --git a/include/constants/pokemon.h b/include/constants/pokemon.h
index e32ddf496..c8c25266b 100644
--- a/include/constants/pokemon.h
+++ b/include/constants/pokemon.h
@@ -290,6 +290,12 @@
 
 #define EVOS_PER_MON 5
 
+// Evolution 'modes,' for GetEvolutionTargetSpecies
+#define EVO_MODE_NORMAL     0
+#define EVO_MODE_TRADE      1
+#define EVO_MODE_ITEM_USE   2
+#define EVO_MODE_ITEM_CHECK 3 // If an Everstone is being held, still want to show that the stone *could* be used on that Pokémon to evolve
+
 #define NUM_MALE_LINK_FACILITY_CLASSES   8
 #define NUM_FEMALE_LINK_FACILITY_CLASSES 8
 
diff --git a/src/battle_main.c b/src/battle_main.c
index a415d894f..dd056243b 100644
--- a/src/battle_main.c
+++ b/src/battle_main.c
@@ -5105,7 +5105,7 @@ static void TryEvolvePokemon(void)
                 levelUpBits &= ~(gBitTable[i]);
                 gLeveledUpInBattle = levelUpBits;
 
-                species = GetEvolutionTargetSpecies(&gPlayerParty[i], 0, levelUpBits);
+                species = GetEvolutionTargetSpecies(&gPlayerParty[i], EVO_MODE_NORMAL, levelUpBits);
                 if (species != SPECIES_NONE)
                 {
                     FreeAllWindowBuffers();
diff --git a/src/battle_script_commands.c b/src/battle_script_commands.c
index d0aa9164a..6df240d65 100644
--- a/src/battle_script_commands.c
+++ b/src/battle_script_commands.c
@@ -6245,7 +6245,7 @@ static void Cmd_hpthresholds2(void)
 static void Cmd_useitemonopponent(void)
 {
     gBattlerInMenuId = gBattlerAttacker;
-    PokemonUseItemEffects(&gEnemyParty[gBattlerPartyIndexes[gBattlerAttacker]], gLastUsedItem, gBattlerPartyIndexes[gBattlerAttacker], 0, 1);
+    PokemonUseItemEffects(&gEnemyParty[gBattlerPartyIndexes[gBattlerAttacker]], gLastUsedItem, gBattlerPartyIndexes[gBattlerAttacker], 0, TRUE);
     gBattlescriptCurrInstr += 1;
 }
 
diff --git a/src/data/pokemon/item_effects.h b/src/data/pokemon/item_effects.h
index 1d7f16b90..00872a9b2 100644
--- a/src/data/pokemon/item_effects.h
+++ b/src/data/pokemon/item_effects.h
@@ -1,6 +1,6 @@
 const u8 gItemEffect_Potion[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 20,
+    [6] = 20, // Amount of HP to recover
 };
 
 const u8 gItemEffect_Antidote[6] = {
@@ -26,22 +26,22 @@ const u8 gItemEffect_ParalyzeHeal[6] = {
 const u8 gItemEffect_FullRestore[7] = {
     [3] = ITEM3_STATUS_ALL,
     [4] = ITEM4_HEAL_HP,
-    [6] = ITEM6_HEAL_FULL,
+    [6] = ITEM6_HEAL_HP_FULL,
 };
 
 const u8 gItemEffect_MaxPotion[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = ITEM6_HEAL_FULL,
+    [6] = ITEM6_HEAL_HP_FULL,
 };
 
 const u8 gItemEffect_HyperPotion[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 200,
+    [6] = 200, // Amount of HP to recover
 };
 
 const u8 gItemEffect_SuperPotion[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 50,
+    [6] = 50, // Amount of HP to recover
 };
 
 const u8 gItemEffect_FullHeal[6] = {
@@ -50,87 +50,87 @@ const u8 gItemEffect_FullHeal[6] = {
 
 const u8 gItemEffect_Revive[7] = {
     [4] = ITEM4_REVIVE | ITEM4_HEAL_HP,
-    [6] = ITEM6_HEAL_HALF,
+    [6] = ITEM6_HEAL_HP_HALF,
 };
 
 const u8 gItemEffect_MaxRevive[7] = {
     [4] = ITEM4_REVIVE | ITEM4_HEAL_HP,
-    [6] = ITEM6_HEAL_FULL,
+    [6] = ITEM6_HEAL_HP_FULL,
 };
 
 const u8 gItemEffect_FreshWater[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 50,
+    [6] = 50, // Amount of HP to recover
 };
 
 const u8 gItemEffect_SodaPop[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 60,
+    [6] = 60, // Amount of HP to recover
 };
 
 const u8 gItemEffect_Lemonade[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 80,
+    [6] = 80, // Amount of HP to recover
 };
 
 const u8 gItemEffect_MoomooMilk[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 100,
+    [6] = 100, // Amount of HP to recover
 };
 
 const u8 gItemEffect_EnergyPowder[10] = {
     [4] = ITEM4_HEAL_HP,
     [5] = ITEM5_FRIENDSHIP_ALL,
-    [6] = 50,
-    [7] = -5,
-    [8] = -5,
-    [9] = -10,
+    [6] = 50,  // Amount of HP to recover
+    [7] = -5,  // Friendship change, low
+    [8] = -5,  // Friendship change, mid
+    [9] = -10, // Friendship change, high
 };
 
 const u8 gItemEffect_EnergyRoot[10] = {
     [4] = ITEM4_HEAL_HP,
     [5] = ITEM5_FRIENDSHIP_ALL,
-    [6] = 200,
-    [7] = -10,
-    [8] = -10,
-    [9] = -15,
+    [6] = 200, // Amount of HP to recover
+    [7] = -10, // Friendship change, low
+    [8] = -10, // Friendship change, mid
+    [9] = -15, // Friendship change, high
 };
 
 const u8 gItemEffect_HealPowder[9] = {
     [3] = ITEM3_STATUS_ALL,
     [5] = ITEM5_FRIENDSHIP_ALL,
-    [6] = -5,
-    [7] = -5,
-    [8] = -10,
+    [6] = -5,  // Friendship change, low
+    [7] = -5,  // Friendship change, mid
+    [8] = -10, // Friendship change, high
 };
 
 const u8 gItemEffect_RevivalHerb[10] = {
     [4] = ITEM4_REVIVE | ITEM4_HEAL_HP,
     [5] = ITEM5_FRIENDSHIP_ALL,
-    [6] = ITEM6_HEAL_FULL,
-    [7] = -15,
-    [8] = -15,
-    [9] = -20,
+    [6] = ITEM6_HEAL_HP_FULL,
+    [7] = -15, // Friendship change, low
+    [8] = -15, // Friendship change, mid
+    [9] = -20, // Friendship change, high
 };
 
 const u8 gItemEffect_Ether[7] = {
-    [4] = ITEM4_HEAL_PP_ONE | ITEM4_HEAL_PP_ALL,
+    [4] = ITEM4_HEAL_PP_ONE | ITEM4_HEAL_PP,
     [6] = 10,
 };
 
 const u8 gItemEffect_MaxEther[7] = {
-    [4] = ITEM4_HEAL_PP_ONE | ITEM4_HEAL_PP_ALL,
-    [6] = 0x7F,
+    [4] = ITEM4_HEAL_PP_ONE | ITEM4_HEAL_PP,
+    [6] = ITEM6_HEAL_PP_FULL,
 };
 
 const u8 gItemEffect_Elixir[7] = {
-    [4] = ITEM4_HEAL_PP_ALL,
-    [6] = 10,
+    [4] = ITEM4_HEAL_PP,
+    [6] = 10, // Amount of PP to recover
 };
 
 const u8 gItemEffect_MaxElixir[7] = {
-    [4] = ITEM4_HEAL_PP_ALL,
-    [6] = 0x7F,
+    [4] = ITEM4_HEAL_PP,
+    [6] = ITEM6_HEAL_PP_FULL,
 };
 
 const u8 gItemEffect_LavaCookie[6] = {
@@ -151,137 +151,125 @@ const u8 gItemEffect_RedFlute[6] = {
 
 const u8 gItemEffect_BerryJuice[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 20,
+    [6] = 20, // Amount of HP to recover
 };
 
 const u8 gItemEffect_SacredAsh[7] = {
     [0] = ITEM0_SACRED_ASH,
     [4] = ITEM4_REVIVE | ITEM4_HEAL_HP,
-    [6] = ITEM6_HEAL_FULL,
+    [6] = ITEM6_HEAL_HP_FULL,
 };
 
+#define VITAMIN_FRIENDSHIP_CHANGE(i)             \
+    [(i) + 0] = 5, /* Friendship change, low */  \
+    [(i) + 1] = 3, /* Friendship change, mid */  \
+    [(i) + 2] = 2  /* Friendship change, high */
+
 const u8 gItemEffect_HPUp[10] = {
     [4] = ITEM4_EV_HP,
     [5] = ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_ADD_EV,
-    [7] = 5,
-    [8] = 3,
-    [9] = 2,
+    VITAMIN_FRIENDSHIP_CHANGE(7),
 };
 
 const u8 gItemEffect_Protein[10] = {
     [4] = ITEM4_EV_ATK,
     [5] = ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_ADD_EV,
-    [7] = 5,
-    [8] = 3,
-    [9] = 2,
+    VITAMIN_FRIENDSHIP_CHANGE(7),
 };
 
 const u8 gItemEffect_Iron[10] = {
     [5] = ITEM5_EV_DEF | ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_ADD_EV,
-    [7] = 5,
-    [8] = 3,
-    [9] = 2,
+    VITAMIN_FRIENDSHIP_CHANGE(7),
 };
 
 const u8 gItemEffect_Carbos[10] = {
     [5] = ITEM5_EV_SPEED | ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_ADD_EV,
-    [7] = 5,
-    [8] = 3,
-    [9] = 2,
+    VITAMIN_FRIENDSHIP_CHANGE(7),
 };
 
 const u8 gItemEffect_Calcium[10] = {
     [5] = ITEM5_EV_SPATK | ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_ADD_EV,
-    [7] = 5,
-    [8] = 3,
-    [9] = 2,
+    VITAMIN_FRIENDSHIP_CHANGE(7),
 };
 
 const u8 gItemEffect_RareCandy[10] = {
     [3] = ITEM3_LEVEL_UP,
     [4] = ITEM4_REVIVE | ITEM4_HEAL_HP,
     [5] = ITEM5_FRIENDSHIP_ALL,
-    [6] = ITEM6_HEAL_LVL_UP,
-    [7] = 5,
-    [8] = 3,
-    [9] = 2,
+    [6] = ITEM6_HEAL_HP_LVL_UP,
+    VITAMIN_FRIENDSHIP_CHANGE(7),
 };
 
 const u8 gItemEffect_PPUp[9] = {
     [4] = ITEM4_PP_UP,
     [5] = ITEM5_FRIENDSHIP_ALL,
-    [6] = 5,
-    [7] = 3,
-    [8] = 2,
+    VITAMIN_FRIENDSHIP_CHANGE(6),
 };
 
 const u8 gItemEffect_Zinc[10] = {
     [5] = ITEM5_EV_SPDEF | ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_ADD_EV,
-    [7] = 5,
-    [8] = 3,
-    [9] = 2,
+    VITAMIN_FRIENDSHIP_CHANGE(7),
 };
 
 const u8 gItemEffect_PPMax[9] = {
     [5] = ITEM5_PP_MAX | ITEM5_FRIENDSHIP_ALL,
-    [6] = 5,
-    [7] = 3,
-    [8] = 2,
+    VITAMIN_FRIENDSHIP_CHANGE(6),
 };
 
+#define STAT_BOOST_FRIENDSHIP_CHANGE      \
+    [6] = 1, /* Friendship change, low */ \
+    [7] = 1  /* Friendship change, mid */
+
 const u8 gItemEffect_GuardSpec[8] = {
     [3] = ITEM3_GUARD_SPEC,
     [5] = ITEM5_FRIENDSHIP_LOW | ITEM5_FRIENDSHIP_MID,
-    [6] = 1,
-    [7] = 1,
+    STAT_BOOST_FRIENDSHIP_CHANGE,
 };
 
+// The first item effect value for the stat boost items
+// only uses the least significant bit of its full mask.
+// The full constant is commented next to it
+
 const u8 gItemEffect_DireHit[8] = {
-    [0] = 2 << 4,
+    [0] = 1 << 5, // ITEM0_DIRE_HIT
     [5] = ITEM5_FRIENDSHIP_LOW | ITEM5_FRIENDSHIP_MID,
-    [6] = 1,
-    [7] = 1,
+    STAT_BOOST_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_XAttack[8] = {
-    [0] = 1,
+    [0] = 1, // ITEM0_X_ATTACK
     [5] = ITEM5_FRIENDSHIP_LOW | ITEM5_FRIENDSHIP_MID,
-    [6] = 1,
-    [7] = 1,
+    STAT_BOOST_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_XDefend[8] = {
-    [1] = 1 << 4,
+    [1] = 1 << 4, /// ITEM1_X_DEFEND
     [5] = ITEM5_FRIENDSHIP_LOW | ITEM5_FRIENDSHIP_MID,
-    [6] = 1,
-    [7] = 1,
+    STAT_BOOST_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_XSpeed[8] = {
-    [1] = 1,
+    [1] = 1, // ITEM1_X_SPEED
     [5] = ITEM5_FRIENDSHIP_LOW | ITEM5_FRIENDSHIP_MID,
-    [6] = 1,
-    [7] = 1,
+    STAT_BOOST_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_XAccuracy[8] = {
-    [2] = 1 << 4,
+    [2] = 1 << 4, // ITEM2_X_ACCURACY
     [5] = ITEM5_FRIENDSHIP_LOW | ITEM5_FRIENDSHIP_MID,
-    [6] = 1,
-    [7] = 1,
+    STAT_BOOST_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_XSpecial[8] = {
-    [2] = 1,
+    [2] = 1, // ITEM2_X_SPATK
     [5] = ITEM5_FRIENDSHIP_LOW | ITEM5_FRIENDSHIP_MID,
-    [6] = 1,
-    [7] = 1,
+    STAT_BOOST_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_SunStone[6] = {
@@ -329,13 +317,13 @@ const u8 gItemEffect_AspearBerry[6] = {
 };
 
 const u8 gItemEffect_LeppaBerry[7] = {
-    [4] = ITEM4_HEAL_PP_ONE | ITEM4_HEAL_PP_ALL,
-    [6] = 10,
+    [4] = ITEM4_HEAL_PP_ONE | ITEM4_HEAL_PP,
+    [6] = 10, // Amount of PP to recover
 };
 
 const u8 gItemEffect_OranBerry[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 10,
+    [6] = 10, // Amount of HP to recover
 };
 
 const u8 gItemEffect_PersimBerry[6] = {
@@ -348,129 +336,122 @@ const u8 gItemEffect_LumBerry[6] = {
 
 const u8 gItemEffect_SitrusBerry[7] = {
     [4] = ITEM4_HEAL_HP,
-    [6] = 30,
+    [6] = 30, // Amount of HP to recover
 };
 
+#define EV_BERRY_FRIENDSHIP_CHANGE          \
+    [7] = 10, /* Friendship change, low */  \
+    [8] = 5,  /* Friendship change, mid */  \
+    [9] = 2   /* Friendship change, high */
+
 const u8 gItemEffect_PomegBerry[10] = {
     [4] = ITEM4_EV_HP,
     [5] = ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_SUBTRACT_EV,
-    [7] = 10,
-    [8] = 5,
-    [9] = 2,
+    EV_BERRY_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_KelpsyBerry[10] = {
     [4] = ITEM4_EV_ATK,
     [5] = ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_SUBTRACT_EV,
-    [7] = 10,
-    [8] = 5,
-    [9] = 2,
+    EV_BERRY_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_QualotBerry[10] = {
     [5] = ITEM5_EV_DEF | ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_SUBTRACT_EV,
-    [7] = 10,
-    [8] = 5,
-    [9] = 2,
+    EV_BERRY_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_HondewBerry[10] = {
     [5] = ITEM5_EV_SPATK | ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_SUBTRACT_EV,
-    [7] = 10,
-    [8] = 5,
-    [9] = 2,
+    EV_BERRY_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_GrepaBerry[10] = {
     [5] = ITEM5_EV_SPDEF | ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_SUBTRACT_EV,
-    [7] = 10,
-    [8] = 5,
-    [9] = 2,
+    EV_BERRY_FRIENDSHIP_CHANGE,
 };
 
 const u8 gItemEffect_TamatoBerry[10] = {
     [5] = ITEM5_EV_SPEED | ITEM5_FRIENDSHIP_ALL,
     [6] = ITEM6_SUBTRACT_EV,
-    [7] = 10,
-    [8] = 5,
-    [9] = 2,
+    EV_BERRY_FRIENDSHIP_CHANGE,
 };
 
 const u8 *const gItemEffectTable[] =
 {
-    [ITEM_POTION - ITEM_POTION] = gItemEffect_Potion,
-    [ITEM_ANTIDOTE - ITEM_POTION] = gItemEffect_Antidote,
-    [ITEM_BURN_HEAL - ITEM_POTION] = gItemEffect_BurnHeal,
-    [ITEM_ICE_HEAL - ITEM_POTION] = gItemEffect_IceHeal,
-    [ITEM_AWAKENING - ITEM_POTION] = gItemEffect_Awakening,
+    [ITEM_POTION - ITEM_POTION]        = gItemEffect_Potion,
+    [ITEM_ANTIDOTE - ITEM_POTION]      = gItemEffect_Antidote,
+    [ITEM_BURN_HEAL - ITEM_POTION]     = gItemEffect_BurnHeal,
+    [ITEM_ICE_HEAL - ITEM_POTION]      = gItemEffect_IceHeal,
+    [ITEM_AWAKENING - ITEM_POTION]     = gItemEffect_Awakening,
     [ITEM_PARALYZE_HEAL - ITEM_POTION] = gItemEffect_ParalyzeHeal,
-    [ITEM_FULL_RESTORE - ITEM_POTION] = gItemEffect_FullRestore,
-    [ITEM_MAX_POTION - ITEM_POTION] = gItemEffect_MaxPotion,
-    [ITEM_HYPER_POTION - ITEM_POTION] = gItemEffect_HyperPotion,
-    [ITEM_SUPER_POTION - ITEM_POTION] = gItemEffect_SuperPotion,
-    [ITEM_FULL_HEAL - ITEM_POTION] = gItemEffect_FullHeal,
-    [ITEM_REVIVE - ITEM_POTION] = gItemEffect_Revive,
-    [ITEM_MAX_REVIVE - ITEM_POTION] = gItemEffect_MaxRevive,
-    [ITEM_FRESH_WATER - ITEM_POTION] = gItemEffect_FreshWater,
-    [ITEM_SODA_POP - ITEM_POTION] = gItemEffect_SodaPop,
-    [ITEM_LEMONADE - ITEM_POTION] = gItemEffect_Lemonade,
-    [ITEM_MOOMOO_MILK - ITEM_POTION] = gItemEffect_MoomooMilk,
+    [ITEM_FULL_RESTORE - ITEM_POTION]  = gItemEffect_FullRestore,
+    [ITEM_MAX_POTION - ITEM_POTION]    = gItemEffect_MaxPotion,
+    [ITEM_HYPER_POTION - ITEM_POTION]  = gItemEffect_HyperPotion,
+    [ITEM_SUPER_POTION - ITEM_POTION]  = gItemEffect_SuperPotion,
+    [ITEM_FULL_HEAL - ITEM_POTION]     = gItemEffect_FullHeal,
+    [ITEM_REVIVE - ITEM_POTION]        = gItemEffect_Revive,
+    [ITEM_MAX_REVIVE - ITEM_POTION]    = gItemEffect_MaxRevive,
+    [ITEM_FRESH_WATER - ITEM_POTION]   = gItemEffect_FreshWater,
+    [ITEM_SODA_POP - ITEM_POTION]      = gItemEffect_SodaPop,
+    [ITEM_LEMONADE - ITEM_POTION]      = gItemEffect_Lemonade,
+    [ITEM_MOOMOO_MILK - ITEM_POTION]   = gItemEffect_MoomooMilk,
     [ITEM_ENERGY_POWDER - ITEM_POTION] = gItemEffect_EnergyPowder,
-    [ITEM_ENERGY_ROOT - ITEM_POTION] = gItemEffect_EnergyRoot,
-    [ITEM_HEAL_POWDER - ITEM_POTION] = gItemEffect_HealPowder,
-    [ITEM_REVIVAL_HERB - ITEM_POTION] = gItemEffect_RevivalHerb,
-    [ITEM_ETHER - ITEM_POTION] = gItemEffect_Ether,
-    [ITEM_MAX_ETHER - ITEM_POTION] = gItemEffect_MaxEther,
-    [ITEM_ELIXIR - ITEM_POTION] = gItemEffect_Elixir,
-    [ITEM_MAX_ELIXIR - ITEM_POTION] = gItemEffect_MaxElixir,
-    [ITEM_LAVA_COOKIE - ITEM_POTION] = gItemEffect_LavaCookie,
-    [ITEM_BLUE_FLUTE - ITEM_POTION] = gItemEffect_BlueFlute,
-    [ITEM_YELLOW_FLUTE - ITEM_POTION] = gItemEffect_YellowFlute,
-    [ITEM_RED_FLUTE - ITEM_POTION] = gItemEffect_RedFlute,
-    [ITEM_BERRY_JUICE - ITEM_POTION] = gItemEffect_BerryJuice,
-    [ITEM_SACRED_ASH - ITEM_POTION] = gItemEffect_SacredAsh,
-    [ITEM_HP_UP - ITEM_POTION] = gItemEffect_HPUp,
-    [ITEM_PROTEIN - ITEM_POTION] = gItemEffect_Protein,
-    [ITEM_IRON - ITEM_POTION] = gItemEffect_Iron,
-    [ITEM_CARBOS - ITEM_POTION] = gItemEffect_Carbos,
-    [ITEM_CALCIUM - ITEM_POTION] = gItemEffect_Calcium,
-    [ITEM_RARE_CANDY - ITEM_POTION] = gItemEffect_RareCandy,
-    [ITEM_PP_UP - ITEM_POTION] = gItemEffect_PPUp,
-    [ITEM_ZINC - ITEM_POTION] = gItemEffect_Zinc,
-    [ITEM_PP_MAX - ITEM_POTION] = gItemEffect_PPMax,
-    [ITEM_GUARD_SPEC - ITEM_POTION] = gItemEffect_GuardSpec,
-    [ITEM_DIRE_HIT - ITEM_POTION] = gItemEffect_DireHit,
-    [ITEM_X_ATTACK - ITEM_POTION] = gItemEffect_XAttack,
-    [ITEM_X_DEFEND - ITEM_POTION] = gItemEffect_XDefend,
-    [ITEM_X_SPEED - ITEM_POTION] = gItemEffect_XSpeed,
-    [ITEM_X_ACCURACY - ITEM_POTION] = gItemEffect_XAccuracy,
-    [ITEM_X_SPECIAL - ITEM_POTION] = gItemEffect_XSpecial,
-    [ITEM_SUN_STONE - ITEM_POTION] = gItemEffect_SunStone,
-    [ITEM_MOON_STONE - ITEM_POTION] = gItemEffect_MoonStone,
-    [ITEM_FIRE_STONE - ITEM_POTION] = gItemEffect_FireStone,
+    [ITEM_ENERGY_ROOT - ITEM_POTION]   = gItemEffect_EnergyRoot,
+    [ITEM_HEAL_POWDER - ITEM_POTION]   = gItemEffect_HealPowder,
+    [ITEM_REVIVAL_HERB - ITEM_POTION]  = gItemEffect_RevivalHerb,
+    [ITEM_ETHER - ITEM_POTION]         = gItemEffect_Ether,
+    [ITEM_MAX_ETHER - ITEM_POTION]     = gItemEffect_MaxEther,
+    [ITEM_ELIXIR - ITEM_POTION]        = gItemEffect_Elixir,
+    [ITEM_MAX_ELIXIR - ITEM_POTION]    = gItemEffect_MaxElixir,
+    [ITEM_LAVA_COOKIE - ITEM_POTION]   = gItemEffect_LavaCookie,
+    [ITEM_BLUE_FLUTE - ITEM_POTION]    = gItemEffect_BlueFlute,
+    [ITEM_YELLOW_FLUTE - ITEM_POTION]  = gItemEffect_YellowFlute,
+    [ITEM_RED_FLUTE - ITEM_POTION]     = gItemEffect_RedFlute,
+    [ITEM_BERRY_JUICE - ITEM_POTION]   = gItemEffect_BerryJuice,
+    [ITEM_SACRED_ASH - ITEM_POTION]    = gItemEffect_SacredAsh,
+    [ITEM_HP_UP - ITEM_POTION]         = gItemEffect_HPUp,
+    [ITEM_PROTEIN - ITEM_POTION]       = gItemEffect_Protein,
+    [ITEM_IRON - ITEM_POTION]          = gItemEffect_Iron,
+    [ITEM_CARBOS - ITEM_POTION]        = gItemEffect_Carbos,
+    [ITEM_CALCIUM - ITEM_POTION]       = gItemEffect_Calcium,
+    [ITEM_RARE_CANDY - ITEM_POTION]    = gItemEffect_RareCandy,
+    [ITEM_PP_UP - ITEM_POTION]         = gItemEffect_PPUp,
+    [ITEM_ZINC - ITEM_POTION]          = gItemEffect_Zinc,
+    [ITEM_PP_MAX - ITEM_POTION]        = gItemEffect_PPMax,
+    [ITEM_GUARD_SPEC - ITEM_POTION]    = gItemEffect_GuardSpec,
+    [ITEM_DIRE_HIT - ITEM_POTION]      = gItemEffect_DireHit,
+    [ITEM_X_ATTACK - ITEM_POTION]      = gItemEffect_XAttack,
+    [ITEM_X_DEFEND - ITEM_POTION]      = gItemEffect_XDefend,
+    [ITEM_X_SPEED - ITEM_POTION]       = gItemEffect_XSpeed,
+    [ITEM_X_ACCURACY - ITEM_POTION]    = gItemEffect_XAccuracy,
+    [ITEM_X_SPECIAL - ITEM_POTION]     = gItemEffect_XSpecial,
+    [ITEM_SUN_STONE - ITEM_POTION]     = gItemEffect_SunStone,
+    [ITEM_MOON_STONE - ITEM_POTION]    = gItemEffect_MoonStone,
+    [ITEM_FIRE_STONE - ITEM_POTION]    = gItemEffect_FireStone,
     [ITEM_THUNDER_STONE - ITEM_POTION] = gItemEffect_ThunderStone,
-    [ITEM_WATER_STONE - ITEM_POTION] = gItemEffect_WaterStone,
-    [ITEM_LEAF_STONE - ITEM_POTION] = gItemEffect_LeafStone,
-    [ITEM_CHERI_BERRY - ITEM_POTION] = gItemEffect_CheriBerry,
-    [ITEM_CHESTO_BERRY - ITEM_POTION] = gItemEffect_ChestoBerry,
-    [ITEM_PECHA_BERRY - ITEM_POTION] = gItemEffect_PechaBerry,
-    [ITEM_RAWST_BERRY - ITEM_POTION] = gItemEffect_RawstBerry,
-    [ITEM_ASPEAR_BERRY - ITEM_POTION] = gItemEffect_AspearBerry,
-    [ITEM_LEPPA_BERRY - ITEM_POTION] = gItemEffect_LeppaBerry,
-    [ITEM_ORAN_BERRY - ITEM_POTION] = gItemEffect_OranBerry,
-    [ITEM_PERSIM_BERRY - ITEM_POTION] = gItemEffect_PersimBerry,
-    [ITEM_LUM_BERRY - ITEM_POTION] = gItemEffect_LumBerry,
-    [ITEM_SITRUS_BERRY - ITEM_POTION] = gItemEffect_SitrusBerry,
-    [ITEM_POMEG_BERRY - ITEM_POTION] = gItemEffect_PomegBerry,
-    [ITEM_KELPSY_BERRY - ITEM_POTION] = gItemEffect_KelpsyBerry,
-    [ITEM_QUALOT_BERRY - ITEM_POTION] = gItemEffect_QualotBerry,
-    [ITEM_HONDEW_BERRY - ITEM_POTION] = gItemEffect_HondewBerry,
-    [ITEM_GREPA_BERRY - ITEM_POTION] = gItemEffect_GrepaBerry,
-    [ITEM_TAMATO_BERRY - ITEM_POTION] = gItemEffect_TamatoBerry,
-    [LAST_BERRY_INDEX - ITEM_POTION] = NULL
+    [ITEM_WATER_STONE - ITEM_POTION]   = gItemEffect_WaterStone,
+    [ITEM_LEAF_STONE - ITEM_POTION]    = gItemEffect_LeafStone,
+    [ITEM_CHERI_BERRY - ITEM_POTION]   = gItemEffect_CheriBerry,
+    [ITEM_CHESTO_BERRY - ITEM_POTION]  = gItemEffect_ChestoBerry,
+    [ITEM_PECHA_BERRY - ITEM_POTION]   = gItemEffect_PechaBerry,
+    [ITEM_RAWST_BERRY - ITEM_POTION]   = gItemEffect_RawstBerry,
+    [ITEM_ASPEAR_BERRY - ITEM_POTION]  = gItemEffect_AspearBerry,
+    [ITEM_LEPPA_BERRY - ITEM_POTION]   = gItemEffect_LeppaBerry,
+    [ITEM_ORAN_BERRY - ITEM_POTION]    = gItemEffect_OranBerry,
+    [ITEM_PERSIM_BERRY - ITEM_POTION]  = gItemEffect_PersimBerry,
+    [ITEM_LUM_BERRY - ITEM_POTION]     = gItemEffect_LumBerry,
+    [ITEM_SITRUS_BERRY - ITEM_POTION]  = gItemEffect_SitrusBerry,
+    [ITEM_POMEG_BERRY - ITEM_POTION]   = gItemEffect_PomegBerry,
+    [ITEM_KELPSY_BERRY - ITEM_POTION]  = gItemEffect_KelpsyBerry,
+    [ITEM_QUALOT_BERRY - ITEM_POTION]  = gItemEffect_QualotBerry,
+    [ITEM_HONDEW_BERRY - ITEM_POTION]  = gItemEffect_HondewBerry,
+    [ITEM_GREPA_BERRY - ITEM_POTION]   = gItemEffect_GrepaBerry,
+    [ITEM_TAMATO_BERRY - ITEM_POTION]  = gItemEffect_TamatoBerry,
+    [LAST_BERRY_INDEX - ITEM_POTION]   = NULL
 };
diff --git a/src/party_menu.c b/src/party_menu.c
index b2fd358ca..95c41ac05 100755
--- a/src/party_menu.c
+++ b/src/party_menu.c
@@ -915,7 +915,7 @@ static bool8 DisplayPartyPokemonDataForMoveTutorOrEvolutionItem(u8 slot)
             DisplayPartyPokemonDataToTeachMove(slot, item, 0);
             break;
         case 2: // Evolution stone
-            if (!GetMonData(currentPokemon, MON_DATA_IS_EGG) && GetEvolutionTargetSpecies(currentPokemon, 3, item) != SPECIES_NONE)
+            if (!GetMonData(currentPokemon, MON_DATA_IS_EGG) && GetEvolutionTargetSpecies(currentPokemon, EVO_MODE_ITEM_CHECK, item) != SPECIES_NONE)
                 return FALSE;
             DisplayPartyPokemonDescriptionData(slot, PARTYBOX_DESC_NO_USE);
             break;
@@ -5018,13 +5018,13 @@ static void Task_TryLearningNextMove(u8 taskId)
 static void PartyMenuTryEvolution(u8 taskId)
 {
     struct Pokemon *mon = &gPlayerParty[gPartyMenu.slotId];
-    u16 targetSpecies = GetEvolutionTargetSpecies(mon, 0, 0);
+    u16 targetSpecies = GetEvolutionTargetSpecies(mon, EVO_MODE_NORMAL, ITEM_NONE);
 
     if (targetSpecies != SPECIES_NONE)
     {
         FreePartyPointers();
         gCB2_AfterEvolution = gPartyMenu.exitCallback;
-        BeginEvolutionScene(mon, targetSpecies, 1, gPartyMenu.slotId);
+        BeginEvolutionScene(mon, targetSpecies, TRUE, gPartyMenu.slotId);
         DestroyTask(taskId);
     }
     else
@@ -5232,7 +5232,7 @@ u8 GetItemEffectType(u16 item)
         return ITEM_EFFECT_PP_UP;
     else if (itemEffect[5] & ITEM5_PP_MAX)
         return ITEM_EFFECT_PP_MAX;
-    else if (itemEffect[4] & (ITEM4_HEAL_PP_ALL | ITEM4_HEAL_PP_ONE))
+    else if (itemEffect[4] & (ITEM4_HEAL_PP | ITEM4_HEAL_PP_ONE))
         return ITEM_EFFECT_HEAL_PP;
     else
         return ITEM_EFFECT_NONE;
diff --git a/src/pokemon.c b/src/pokemon.c
index 5812e987a..29ac4547f 100644
--- a/src/pokemon.c
+++ b/src/pokemon.c
@@ -4640,29 +4640,56 @@ void CopyPlayerPartyMonToBattleData(u8 battlerId, u8 partyIndex)
 
 bool8 ExecuteTableBasedItemEffect(struct Pokemon *mon, u16 item, u8 partyIndex, u8 moveIndex)
 {
-    return PokemonUseItemEffects(mon, item, partyIndex, moveIndex, 0);
-}
-
-bool8 PokemonUseItemEffects(struct Pokemon *mon, u16 item, u8 partyIndex, u8 moveIndex, u8 e)
+    return PokemonUseItemEffects(mon, item, partyIndex, moveIndex, FALSE);
+}
+
+#define UPDATE_FRIENDSHIP_FROM_ITEM                                                                     \
+{                                                                                                       \
+    if ((retVal == 0 || friendshipOnly) && !ShouldSkipFriendshipChange() && friendshipChange == 0)      \
+    {                                                                                                   \
+        friendshipChange = itemEffect[itemEffectParam];                                                 \
+        friendship = GetMonData(mon, MON_DATA_FRIENDSHIP, NULL);                                        \
+        if (friendshipChange > 0 && holdEffect == HOLD_EFFECT_HAPPINESS_UP)                             \
+            friendship += 150 * friendshipChange / 100;                                                 \
+        else                                                                                            \
+            friendship += friendshipChange;                                                             \
+        if (friendshipChange > 0)                                                                       \
+        {                                                                                               \
+            if (GetMonData(mon, MON_DATA_POKEBALL, NULL) == ITEM_LUXURY_BALL)                           \
+                friendship++;                                                                           \
+            if (GetMonData(mon, MON_DATA_MET_LOCATION, NULL) == GetCurrentRegionMapSectionId())         \
+                friendship++;                                                                           \
+        }                                                                                               \
+        if (friendship < 0)                                                                             \
+            friendship = 0;                                                                             \
+        if (friendship > MAX_FRIENDSHIP)                                                                \
+            friendship = MAX_FRIENDSHIP;                                                                \
+        SetMonData(mon, MON_DATA_FRIENDSHIP, &friendship);                                              \
+        retVal = FALSE;                                                                                 \
+    }                                                                                                   \
+}
+
+// Returns TRUE if the item has no effect on the Pokémon, FALSE otherwise
+bool8 PokemonUseItemEffects(struct Pokemon *mon, u16 item, u8 partyIndex, u8 moveIndex, bool8 usedByAI)
 {
     u32 dataUnsigned;
     s32 dataSigned;
     s32 friendship;
-    s32 cmdIndex;
+    s32 i;
     bool8 retVal = TRUE;
     const u8 *itemEffect;
-    u8 var_3C = 6;
-    u32 var_38;
-    s8 var_34 = 0;
+    u8 itemEffectParam = ITEM_EFFECT_ARG_START;
+    u32 temp1, temp2;
+    s8 friendshipChange = 0;
     u8 holdEffect;
-    u8 battlerId = 4;
-    u32 var_28 = 0;
+    u8 battlerId = MAX_BATTLERS_COUNT;
+    u32 friendshipOnly = FALSE;
     u16 heldItem;
-    u8 r10;
-    u32 r5;
-    s8 r2;
+    u8 effectFlags;
+    s8 evChange;
     u16 evCount;
 
+    // Get item hold effect
     heldItem = GetMonData(mon, MON_DATA_HELD_ITEM, NULL);
     if (heldItem == ITEM_ENIGMA_BERRY)
     {
@@ -4676,19 +4703,20 @@ bool8 PokemonUseItemEffects(struct Pokemon *mon, u16 item, u8 partyIndex, u8 mov
         holdEffect = ItemId_GetHoldEffect(heldItem);
     }
 
+    // Get battler id (if relevant)
     gPotentialItemEffectBattler = gBattlerInMenuId;
     if (gMain.inBattle)
     {
         gActiveBattler = gBattlerInMenuId;
-        cmdIndex = (GetBattlerSide(gActiveBattler) != B_SIDE_PLAYER);
-        while (cmdIndex < gBattlersCount)
+        i = (GetBattlerSide(gActiveBattler) != B_SIDE_PLAYER);
+        while (i < gBattlersCount)
         {
-            if (gBattlerPartyIndexes[cmdIndex] == partyIndex)
+            if (gBattlerPartyIndexes[i] == partyIndex)
             {
-                battlerId = cmdIndex;
+                battlerId = i;
                 break;
             }
-            cmdIndex += 2;
+            i += 2;
         }
     }
     else
@@ -4697,11 +4725,13 @@ bool8 PokemonUseItemEffects(struct Pokemon *mon, u16 item, u8 partyIndex, u8 mov
         battlerId = MAX_BATTLERS_COUNT;
     }
 
+    // Skip using the item if it won't do anything
     if (!ITEM_HAS_EFFECT(item))
         return TRUE;
     if (gItemEffectTable[item - ITEM_POTION] == NULL && item != ITEM_ENIGMA_BERRY)
         return TRUE;
 
+    // Get item effect
     if (item == ITEM_ENIGMA_BERRY)
     {
         if (gMain.inBattle)
@@ -4714,79 +4744,98 @@ bool8 PokemonUseItemEffects(struct Pokemon *mon, u16 item, u8 partyIndex, u8 mov
         itemEffect = gItemEffectTable[item - ITEM_POTION];
     }
 
-    for (cmdIndex = 0; cmdIndex < 6; cmdIndex++)
+    // Do item effect
+    for (i = 0; i < ITEM_EFFECT_ARG_START; i++)
     {
-        switch (cmdIndex)
+        switch (i)
         {
-        // infatuation heal, x attack, sacred ash and dire hit
+
+        // Handle ITEM0 effects (infatuation, Dire Hit, X Attack). ITEM0_SACRED_ASH is handled in party_menu.c
         case 0:
-            if ((itemEffect[cmdIndex] & ITEM0_INFATUATION)
+            // Cure infatuation
+            if ((itemEffect[i] & ITEM0_INFATUATION)
              && gMain.inBattle && battlerId != MAX_BATTLERS_COUNT && (gBattleMons[battlerId].status2 & STATUS2_INFATUATION))
             {
                 gBattleMons[battlerId].status2 &= ~STATUS2_INFATUATION;
                 retVal = FALSE;
             }
-            if ((itemEffect[cmdIndex] & ITEM0_DIRE_HIT)
+
+            // Dire Hit
+            if ((itemEffect[i] & ITEM0_DIRE_HIT)
              && !(gBattleMons[gActiveBattler].status2 & STATUS2_FOCUS_ENERGY))
             {
                 gBattleMons[gActiveBattler].status2 |= STATUS2_FOCUS_ENERGY;
                 retVal = FALSE;
             }
-            if ((itemEffect[cmdIndex] & ITEM0_X_ATTACK)
+
+            // X Attack
+            if ((itemEffect[i] & ITEM0_X_ATTACK)
              && gBattleMons[gActiveBattler].statStages[STAT_ATK] < MAX_STAT_STAGE)
             {
-                gBattleMons[gActiveBattler].statStages[STAT_ATK] += itemEffect[cmdIndex] & ITEM0_X_ATTACK;
+                gBattleMons[gActiveBattler].statStages[STAT_ATK] += itemEffect[i] & ITEM0_X_ATTACK;
                 if (gBattleMons[gActiveBattler].statStages[STAT_ATK] > MAX_STAT_STAGE)
                     gBattleMons[gActiveBattler].statStages[STAT_ATK] = MAX_STAT_STAGE;
                 retVal = FALSE;
             }
             break;
-        // in-battle stat boosting effects
+
+        // Handle ITEM1 effects (in-battle stat boosting effects)
         case 1:
-            if ((itemEffect[cmdIndex] & ITEM1_X_DEFEND)
+            // X Defend
+            if ((itemEffect[i] & ITEM1_X_DEFEND)
              && gBattleMons[gActiveBattler].statStages[STAT_DEF] < MAX_STAT_STAGE)
             {
-                gBattleMons[gActiveBattler].statStages[STAT_DEF] += (itemEffect[cmdIndex] & ITEM1_X_DEFEND) >> 4;
+                gBattleMons[gActiveBattler].statStages[STAT_DEF] += (itemEffect[i] & ITEM1_X_DEFEND) >> 4;
                 if (gBattleMons[gActiveBattler].statStages[STAT_DEF] > MAX_STAT_STAGE)
                     gBattleMons[gActiveBattler].statStages[STAT_DEF] = MAX_STAT_STAGE;
                 retVal = FALSE;
             }
-            if ((itemEffect[cmdIndex] & ITEM1_X_SPEED)
+
+            // X Speed
+            if ((itemEffect[i] & ITEM1_X_SPEED)
              && gBattleMons[gActiveBattler].statStages[STAT_SPEED] < MAX_STAT_STAGE)
             {
-                gBattleMons[gActiveBattler].statStages[STAT_SPEED] += itemEffect[cmdIndex] & ITEM1_X_SPEED;
+                gBattleMons[gActiveBattler].statStages[STAT_SPEED] += itemEffect[i] & ITEM1_X_SPEED;
                 if (gBattleMons[gActiveBattler].statStages[STAT_SPEED] > MAX_STAT_STAGE)
                     gBattleMons[gActiveBattler].statStages[STAT_SPEED] = MAX_STAT_STAGE;
                 retVal = FALSE;
             }
             break;
-        // more stat boosting effects
+        // Handle ITEM2 effects (more stat boosting effects)
         case 2:
-            if ((itemEffect[cmdIndex] & ITEM2_X_ACCURACY)
+            // X Accuracy
+            if ((itemEffect[i] & ITEM2_X_ACCURACY)
              && gBattleMons[gActiveBattler].statStages[STAT_ACC] < MAX_STAT_STAGE)
             {
-                gBattleMons[gActiveBattler].statStages[STAT_ACC] += (itemEffect[cmdIndex] & ITEM2_X_ACCURACY) >> 4;
+                gBattleMons[gActiveBattler].statStages[STAT_ACC] += (itemEffect[i] & ITEM2_X_ACCURACY) >> 4;
                 if (gBattleMons[gActiveBattler].statStages[STAT_ACC] > MAX_STAT_STAGE)
                     gBattleMons[gActiveBattler].statStages[STAT_ACC] = MAX_STAT_STAGE;
                 retVal = FALSE;
             }
-            if ((itemEffect[cmdIndex] & ITEM2_X_SPATK)
+
+            // X Sp Attack
+            if ((itemEffect[i] & ITEM2_X_SPATK)
              && gBattleMons[gActiveBattler].statStages[STAT_SPATK] < MAX_STAT_STAGE)
             {
-                gBattleMons[gActiveBattler].statStages[STAT_SPATK] += itemEffect[cmdIndex] & ITEM2_X_SPATK;
+                gBattleMons[gActiveBattler].statStages[STAT_SPATK] += itemEffect[i] & ITEM2_X_SPATK;
                 if (gBattleMons[gActiveBattler].statStages[STAT_SPATK] > MAX_STAT_STAGE)
                     gBattleMons[gActiveBattler].statStages[STAT_SPATK] = MAX_STAT_STAGE;
                 retVal = FALSE;
             }
             break;
+
+        // Handle ITEM3 effects (Guard Spec, Rare Candy, cure status)
         case 3:
-            if ((itemEffect[cmdIndex] & ITEM3_GUARD_SPEC)
+            // Guard Spec
+            if ((itemEffect[i] & ITEM3_GUARD_SPEC)
              && gSideTimers[GetBattlerSide(gActiveBattler)].mistTimer == 0)
             {
                 gSideTimers[GetBattlerSide(gActiveBattler)].mistTimer = 5;
                 retVal = FALSE;
             }
-            if ((itemEffect[cmdIndex] & ITEM3_LEVEL_UP)
+
+            // Rare Candy
+            if ((itemEffect[i] & ITEM3_LEVEL_UP)
              && GetMonData(mon, MON_DATA_LEVEL, NULL) != MAX_LEVEL)
             {
                 dataUnsigned = gExperienceTables[gBaseStats[GetMonData(mon, MON_DATA_SPECIES, NULL)].growthRate][GetMonData(mon, MON_DATA_LEVEL, NULL) + 1];
@@ -4794,106 +4843,120 @@ bool8 PokemonUseItemEffects(struct Pokemon *mon, u16 item, u8 partyIndex, u8 mov
                 CalculateMonStats(mon);
                 retVal = FALSE;
             }
-            if ((itemEffect[cmdIndex] & ITEM3_SLEEP)
-             && HealStatusConditions(mon, partyIndex, 7, battlerId) == 0)
+
+            // Cure status
+            if ((itemEffect[i] & ITEM3_SLEEP)
+             && HealStatusConditions(mon, partyIndex, STATUS1_SLEEP, battlerId) == 0)
             {
-                if (battlerId != 4)
+                if (battlerId != MAX_BATTLERS_COUNT)
                     gBattleMons[battlerId].status2 &= ~STATUS2_NIGHTMARE;
                 retVal = FALSE;
             }
-            if ((itemEffect[cmdIndex] & ITEM3_POISON) && HealStatusConditions(mon, partyIndex, STATUS1_PSN_ANY | STATUS1_TOXIC_COUNTER, battlerId) == 0)
+            if ((itemEffect[i] & ITEM3_POISON) && HealStatusConditions(mon, partyIndex, STATUS1_PSN_ANY | STATUS1_TOXIC_COUNTER, battlerId) == 0)
                 retVal = FALSE;
-            if ((itemEffect[cmdIndex] & ITEM3_BURN) && HealStatusConditions(mon, partyIndex, STATUS1_BURN, battlerId) == 0)
+            if ((itemEffect[i] & ITEM3_BURN) && HealStatusConditions(mon, partyIndex, STATUS1_BURN, battlerId) == 0)
                 retVal = FALSE;
-            if ((itemEffect[cmdIndex] & ITEM3_FREEZE) && HealStatusConditions(mon, partyIndex, STATUS1_FREEZE, battlerId) == 0)
+            if ((itemEffect[i] & ITEM3_FREEZE) && HealStatusConditions(mon, partyIndex, STATUS1_FREEZE, battlerId) == 0)
                 retVal = FALSE;
-            if ((itemEffect[cmdIndex] & ITEM3_PARALYSIS) && HealStatusConditions(mon, partyIndex, STATUS1_PARALYSIS, battlerId) == 0)
+            if ((itemEffect[i] & ITEM3_PARALYSIS) && HealStatusConditions(mon, partyIndex, STATUS1_PARALYSIS, battlerId) == 0)
                 retVal = FALSE;
-            if ((itemEffect[cmdIndex] & ITEM3_CONFUSION)  // heal confusion
+            if ((itemEffect[i] & ITEM3_CONFUSION)  // heal confusion
              && gMain.inBattle && battlerId != MAX_BATTLERS_COUNT && (gBattleMons[battlerId].status2 & STATUS2_CONFUSION))
             {
                 gBattleMons[battlerId].status2 &= ~STATUS2_CONFUSION;
                 retVal = FALSE;
             }
             break;
-        // EV, HP, and PP raising effects
+
+        // Handle ITEM4 effects (Change HP/Atk EVs, HP heal, PP heal, PP up, Revive, and evolution stones)
         case 4:
-            r10 = itemEffect[cmdIndex];
-            if (r10 & ITEM4_PP_UP)
+            effectFlags = itemEffect[i];
+
+            // PP Up
+            if (effectFlags & ITEM4_PP_UP)
             {
-                r10 &= ~ITEM4_PP_UP;
+                effectFlags &= ~ITEM4_PP_UP;
                 dataUnsigned = (GetMonData(mon, MON_DATA_PP_BONUSES, NULL) & gPPUpGetMask[moveIndex]) >> (moveIndex * 2);
-                var_38 = CalculatePPWithBonus(GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL), GetMonData(mon, MON_DATA_PP_BONUSES, NULL), moveIndex);
-                if (dataUnsigned <= 2 && var_38 > 4)
+                temp1 = CalculatePPWithBonus(GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL), GetMonData(mon, MON_DATA_PP_BONUSES, NULL), moveIndex);
+                if (dataUnsigned <= 2 && temp1 > 4)
                 {
                     dataUnsigned = GetMonData(mon, MON_DATA_PP_BONUSES, NULL) + gPPUpAddMask[moveIndex];
                     SetMonData(mon, MON_DATA_PP_BONUSES, &dataUnsigned);
 
-                    dataUnsigned = CalculatePPWithBonus(GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL), dataUnsigned, moveIndex) - var_38;
+                    dataUnsigned = CalculatePPWithBonus(GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL), dataUnsigned, moveIndex) - temp1;
                     dataUnsigned = GetMonData(mon, MON_DATA_PP1 + moveIndex, NULL) + dataUnsigned;
                     SetMonData(mon, MON_DATA_PP1 + moveIndex, &dataUnsigned);
                     retVal = FALSE;
                 }
             }
-            var_38 = 0;
-            while (r10 != 0)
+            temp1 = 0;
+
+            // Loop through and try each of the remaining ITEM4 effects
+            while (effectFlags != 0)
             {
-                if (r10 & 1)
+                if (effectFlags & 1)
                 {
-                    switch (var_38)
+                    switch (temp1)
                     {
-                    case 0:
-                    case 1:
-                        // ev raise
+                    case 0: // ITEM4_EV_HP
+                    case 1: // ITEM4_EV_ATK
                         evCount = GetMonEVCount(mon);
-                        r5 = itemEffect[var_3C];
-                        dataSigned = GetMonData(mon, sGetMonDataEVConstants[var_38], NULL);
-                        r2 = r5;
-                        if (r2 > 0)
+                        temp2 = itemEffect[itemEffectParam];
+                        dataSigned = GetMonData(mon, sGetMonDataEVConstants[temp1], NULL);
+                        evChange = temp2;
+     
+                        if (evChange > 0) // Increasing EV (HP or Atk)
                         {
+                            // Has EV increase limit already been reached?
                             if (evCount >= MAX_TOTAL_EVS)
                                 return TRUE;
                             if (dataSigned >= EV_ITEM_RAISE_LIMIT)
                                 break;
 
-                            if (dataSigned + r2 > EV_ITEM_RAISE_LIMIT)
-                                r5 = EV_ITEM_RAISE_LIMIT - (dataSigned + r2) + r2;
+                            // Limit the increase
+                            if (dataSigned + evChange > EV_ITEM_RAISE_LIMIT)
+                                temp2 = EV_ITEM_RAISE_LIMIT - (dataSigned + evChange) + evChange;
                             else
-                                r5 = r2;
+                                temp2 = evChange;
 
-                            if (evCount + r5 > MAX_TOTAL_EVS)
-                                r5 += MAX_TOTAL_EVS - (evCount + r5);
-                            dataSigned += r5;
+                            if (evCount + temp2 > MAX_TOTAL_EVS)
+                                temp2 += MAX_TOTAL_EVS - (evCount + temp2);
+
+                            dataSigned += temp2;
                         }
-                        else
+                        else // Decreasing EV (HP or Atk)
                         {
                             if (dataSigned == 0)
                             {
-                                var_28 = 1;
-                                var_3C++;
+                                // No EVs to lose, but make sure friendship updates anyway
+                                friendshipOnly = TRUE;
+                                itemEffectParam++;
                                 break;
                             }
-                            dataSigned += r2;
+                            dataSigned += evChange;
                             if (dataSigned < 0)
                                 dataSigned = 0;
                         }
-                        SetMonData(mon, sGetMonDataEVConstants[var_38], &dataSigned);
+
+                        // Update EVs and stats
+                        SetMonData(mon, sGetMonDataEVConstants[temp1], &dataSigned);
                         CalculateMonStats(mon);
-                        var_3C++;
+                        itemEffectParam++;
                         retVal = FALSE;
                         break;
-                    case 2:
-                        // revive
-                        if (r10 & 0x10)
+
+                    case 2: // ITEM4_HEAL_HP
+                        // If Revive, update number of times revive has been used
+                        if (effectFlags & (ITEM4_REVIVE >> 2))
                         {
                             if (GetMonData(mon, MON_DATA_HP, NULL) != 0)
                             {
-                                var_3C++;
+                                itemEffectParam++;
                                 break;
                             }
                             if (gMain.inBattle)
                             {
-                                if (battlerId != 4)
+                                if (battlerId != MAX_BATTLERS_COUNT)
                                 {
                                     gAbsentBattlerFlags &= ~gBitTable[battlerId];
                                     CopyPlayerPartyMonToBattleData(battlerId, GetPartyIdFromBattlePartyId(gBattlerPartyIndexes[battlerId]));
@@ -4912,48 +4975,53 @@ bool8 PokemonUseItemEffects(struct Pokemon *mon, u16 item, u8 partyIndex, u8 mov
                         {
                             if (GetMonData(mon, MON_DATA_HP, NULL) == 0)
                             {
-                                var_3C++;
+                                itemEffectParam++;
                                 break;
                             }
                         }
 
                         // Get amount of HP to restore
-                        dataUnsigned = itemEffect[var_3C++];
+                        dataUnsigned = itemEffect[itemEffectParam++];
                         switch (dataUnsigned)
                         {
-                        case ITEM6_HEAL_FULL:
+                        case ITEM6_HEAL_HP_FULL:
                             dataUnsigned = GetMonData(mon, MON_DATA_MAX_HP, NULL) - GetMonData(mon, MON_DATA_HP, NULL);
                             break;
-                        case ITEM6_HEAL_HALF:
+                        case ITEM6_HEAL_HP_HALF:
                             dataUnsigned = GetMonData(mon, MON_DATA_MAX_HP, NULL) / 2;
                             if (dataUnsigned == 0)
                                 dataUnsigned = 1;
                             break;
-                        case ITEM6_HEAL_LVL_UP:
+                        case ITEM6_HEAL_HP_LVL_UP:
                             dataUnsigned = gBattleScripting.levelUpHP;
                             break;
                         }
+
+                        // Only restore HP if not at max health
                         if (GetMonData(mon, MON_DATA_MAX_HP, NULL) != GetMonData(mon, MON_DATA_HP, NULL))
                         {
-                            if (e == 0)
+                            if (!usedByAI)
                             {
+                                // Restore HP 
                                 dataUnsigned = GetMonData(mon, MON_DATA_HP, NULL) + dataUnsigned;
                                 if (dataUnsigned > GetMonData(mon, MON_DATA_MAX_HP, NULL))
                                     dataUnsigned = GetMonData(mon, MON_DATA_MAX_HP, NULL);
                                 SetMonData(mon, MON_DATA_HP, &dataUnsigned);
-                                if (gMain.inBattle && battlerId != 4)
+
+                                // Update battler (if applicable)
+                                if (gMain.inBattle && battlerId != MAX_BATTLERS_COUNT)
                                 {
                                     gBattleMons[battlerId].hp = dataUnsigned;
-                                    if (!(r10 & 0x10) && GetBattlerSide(gActiveBattler) == B_SIDE_PLAYER)
+                                    if (!(effectFlags & (ITEM4_REVIVE >> 2)) && GetBattlerSide(gActiveBattler) == B_SIDE_PLAYER)
                                     {
                                         if (gBattleResults.numHealingItemsUsed < 255)
                                             gBattleResults.numHealingItemsUsed++;
-                                        // I have to re-use this variable to match.
-                                        r5 = gActiveBattler;
+
+                                        temp2 = gActiveBattler;
                                         gActiveBattler = battlerId;
                                         BtlController_EmitGetMonData(0, REQUEST_ALL_BATTLE, 0);
                                         MarkBattlerForControllerExec(gActiveBattler);
-                                        gActiveBattler = r5;
+                                        gActiveBattler = temp2;
                                     }
                                 }
                             }
@@ -4963,227 +5031,197 @@ bool8 PokemonUseItemEffects(struct Pokemon *mon, u16 item, u8 partyIndex, u8 mov
                             }
                             retVal = FALSE;
                         }
-                        r10 &= 0xEF;
+                        effectFlags &= ~(ITEM4_REVIVE >> 2);
                         break;
-                    case 3:
-                        // Heal pp in all moves.
-                        if (!(r10 & 2))
+
+                    case 3: // ITEM4_HEAL_PP
+                        if (!(effectFlags & (ITEM4_HEAL_PP_ONE >> 3)))
                         {
-                            for (r5 = 0; (signed)(r5) < (signed)(4); r5++)
+                            // Heal PP for all moves
+                            for (temp2 = 0; (signed)(temp2) < (signed)(MAX_MON_MOVES); temp2++)
                             {
                                 u16 moveId;
-
-                                dataUnsigned = GetMonData(mon, MON_DATA_PP1 + r5, NULL);
-                                moveId = GetMonData(mon, MON_DATA_MOVE1 + r5, NULL);
-                                if (dataUnsigned != CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), r5))
+                                dataUnsigned = GetMonData(mon, MON_DATA_PP1 + temp2, NULL);
+                                moveId = GetMonData(mon, MON_DATA_MOVE1 + temp2, NULL);
+                                if (dataUnsigned != CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), temp2))
                                 {
-                                    dataUnsigned += itemEffect[var_3C];
-                                    moveId = GetMonData(mon, MON_DATA_MOVE1 + r5, NULL);
-                                    if (dataUnsigned > CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), r5))
+                                    dataUnsigned += itemEffect[itemEffectParam];
+                                    moveId = GetMonData(mon, MON_DATA_MOVE1 + temp2, NULL); // Redundant
+                                    if (dataUnsigned > CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), temp2))
                                     {
-                                        moveId = GetMonData(mon, MON_DATA_MOVE1 + r5, NULL);
-                                        dataUnsigned = CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), r5);
+                                        moveId = GetMonData(mon, MON_DATA_MOVE1 + temp2, NULL); // Redundant
+                                        dataUnsigned = CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), temp2);
                                     }
-                                    SetMonData(mon, MON_DATA_PP1 + r5, &dataUnsigned);
+                                    SetMonData(mon, MON_DATA_PP1 + temp2, &dataUnsigned);
+
+                                    // Heal battler PP too (if applicable)
                                     if (gMain.inBattle
                                      && battlerId != MAX_BATTLERS_COUNT && !(gBattleMons[battlerId].status2 & STATUS2_TRANSFORMED)
-                                     && !(gDisableStructs[battlerId].mimickedMoves & gBitTable[r5]))
-                                        gBattleMons[battlerId].pp[r5] = dataUnsigned;
+                                     && !(gDisableStructs[battlerId].mimickedMoves & gBitTable[temp2]))
+                                        gBattleMons[battlerId].pp[temp2] = dataUnsigned;
+
                                     retVal = FALSE;
                                 }
                             }
-                            var_3C++;
+                            itemEffectParam++;
                         }
-                        // Heal pp in one move.
                         else
                         {
+                            // Heal PP for one move
                             u16 moveId;
-
                             dataUnsigned = GetMonData(mon, MON_DATA_PP1 + moveIndex, NULL);
                             moveId = GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL);
                             if (dataUnsigned != CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), moveIndex))
                             {
-                                dataUnsigned += itemEffect[var_3C++];
-                                moveId = GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL);
+                                dataUnsigned += itemEffect[itemEffectParam++];
+                                moveId = GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL); // Redundant
                                 if (dataUnsigned > CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), moveIndex))
                                 {
-                                    moveId = GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL);
+                                    moveId = GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL); // Redundant
                                     dataUnsigned = CalculatePPWithBonus(moveId, GetMonData(mon, MON_DATA_PP_BONUSES, NULL), moveIndex);
                                 }
                                 SetMonData(mon, MON_DATA_PP1 + moveIndex, &dataUnsigned);
+                                
+                                // Heal battler PP too (if applicable)
                                 if (gMain.inBattle
-                                 && battlerId != 4 && !(gBattleMons[battlerId].status2 & STATUS2_TRANSFORMED)
+                                 && battlerId != MAX_BATTLERS_COUNT && !(gBattleMons[battlerId].status2 & STATUS2_TRANSFORMED)
                                  && !(gDisableStructs[battlerId].mimickedMoves & gBitTable[moveIndex]))
                                     gBattleMons[battlerId].pp[moveIndex] = dataUnsigned;
+
                                 retVal = FALSE;
                             }
                         }
                         break;
-                        // Evolution stone
-                    case 7:
+
+                    // cases 4-6 are ITEM4_HEAL_PP_ONE, ITEM4_PP_UP, and ITEM4_REVIVE, which
+                    // are already handled above by other cases or before the loop
+
+                    case 7: // ITEM4_EVO_STONE
                         {
-                            u16 targetSpecies = GetEvolutionTargetSpecies(mon, 2, item);
+                            u16 targetSpecies = GetEvolutionTargetSpecies(mon, EVO_MODE_ITEM_USE, item);
 
                             if (targetSpecies != SPECIES_NONE)
                             {
-                                BeginEvolutionScene(mon, targetSpecies, 0, partyIndex);
+                                BeginEvolutionScene(mon, targetSpecies, FALSE, partyIndex);
                                 return FALSE;
                             }
                         }
                         break;
                     }
                 }
-                var_38++;
-                r10 >>= 1;
+                temp1++;
+                effectFlags >>= 1;
             }
             break;
-        // EV and friendship
+
+        // Handle ITEM5 effects (Change Def/SpDef/SpAtk/Speed EVs, PP Max, and friendship changes)
         case 5:
-            r10 = itemEffect[cmdIndex];
-            var_38 = 0;
-            while (r10 != 0)
+            effectFlags = itemEffect[i];
+            temp1 = 0;
+            
+            // Loop through and try each of the ITEM5 effects
+            while (effectFlags != 0)
             {
-                if (r10 & 1)
+                if (effectFlags & 1)
                 {
-                    switch (var_38)
+                    switch (temp1)
                     {
-                    case 0:
-                    case 1:
-                    case 2:
-                    case 3:
+                    case 0: // ITEM5_EV_DEF
+                    case 1: // ITEM5_EV_SPEED
+                    case 2: // ITEM5_EV_SPDEF
+                    case 3: // ITEM5_EV_SPATK
                         evCount = GetMonEVCount(mon);
-                        r5 = itemEffect[var_3C];
-                        dataSigned = GetMonData(mon, sGetMonDataEVConstants[var_38 + 2], NULL);
-                        r2 = r5;
-                        if (r2 > 0)
+                        temp2 = itemEffect[itemEffectParam];
+                        dataSigned = GetMonData(mon, sGetMonDataEVConstants[temp1 + 2], NULL);
+                        evChange = temp2;
+                        if (evChange > 0) // Increasing EV
                         {
+                            // Has EV increase limit already been reached?
                             if (evCount >= MAX_TOTAL_EVS)
                                 return TRUE;
                             if (dataSigned >= EV_ITEM_RAISE_LIMIT)
                                 break;
 
-                            if (dataSigned + r2 > EV_ITEM_RAISE_LIMIT)
-                                r5 = EV_ITEM_RAISE_LIMIT - (dataSigned + r2) + r2;
+                            // Limit the increase
+                            if (dataSigned + evChange > EV_ITEM_RAISE_LIMIT)
+                                temp2 = EV_ITEM_RAISE_LIMIT - (dataSigned + evChange) + evChange;
                             else
-                                r5 = r2;
+                                temp2 = evChange;
 
-                            if (evCount + r5 > MAX_TOTAL_EVS)
-                                r5 += MAX_TOTAL_EVS - (evCount + r5);
-                            dataSigned += r5;
+                            if (evCount + temp2 > MAX_TOTAL_EVS)
+                                temp2 += MAX_TOTAL_EVS - (evCount + temp2);
+
+                            dataSigned += temp2;
                         }
-                        else
+                        else // Decreasing EV
                         {
                             if (dataSigned == 0)
                             {
-                                var_28 = 1;
-                                var_3C++;
+                                // No EVs to lose, but make sure friendship updates anyway
+                                friendshipOnly = TRUE;
+                                itemEffectParam++;
                                 break;
                             }
-                            dataSigned += r2;
+                            dataSigned += evChange;
                             if (dataSigned < 0)
                                 dataSigned = 0;
                         }
-                        SetMonData(mon, sGetMonDataEVConstants[var_38 + 2], &dataSigned);
+
+                        // Update EVs and stats
+                        SetMonData(mon, sGetMonDataEVConstants[temp1 + 2], &dataSigned);
                         CalculateMonStats(mon);
                         retVal = FALSE;
-                        var_3C++;
+                        itemEffectParam++;
                         break;
-                    case 4:
+
+                    case 4: // ITEM5_PP_MAX
                         dataUnsigned = (GetMonData(mon, MON_DATA_PP_BONUSES, NULL) & gPPUpGetMask[moveIndex]) >> (moveIndex * 2);
-                        r5 = CalculatePPWithBonus(GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL), GetMonData(mon, MON_DATA_PP_BONUSES, NULL), moveIndex);
-                        if (dataUnsigned < 3 && r5 > 4)
+                        temp2 = CalculatePPWithBonus(GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL), GetMonData(mon, MON_DATA_PP_BONUSES, NULL), moveIndex);
+                        if (dataUnsigned < 3 && temp2 > 4)
                         {
                             dataUnsigned = GetMonData(mon, MON_DATA_PP_BONUSES, NULL);
                             dataUnsigned &= gPPUpSetMask[moveIndex];
                             dataUnsigned += gPPUpAddMask[moveIndex] * 3;
 
                             SetMonData(mon, MON_DATA_PP_BONUSES, &dataUnsigned);
-                            dataUnsigned = CalculatePPWithBonus(GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL), dataUnsigned, moveIndex) - r5;
+                            dataUnsigned = CalculatePPWithBonus(GetMonData(mon, MON_DATA_MOVE1 + moveIndex, NULL), dataUnsigned, moveIndex) - temp2;
                             dataUnsigned = GetMonData(mon, MON_DATA_PP1 + moveIndex, NULL) + dataUnsigned;
                             SetMonData(mon, MON_DATA_PP1 + moveIndex, &dataUnsigned);
                             retVal = FALSE;
                         }
                         break;
-                    case 5:
-                        if (GetMonData(mon, MON_DATA_FRIENDSHIP, NULL) < 100 && (retVal == 0 || var_28 != 0) && !ShouldSkipFriendshipChange() && var_34 == 0)
+
+                    case 5: // ITEM5_FRIENDSHIP_LOW
+                        // Changes to friendship are given differently depending on
+                        // how much friendship the Pokémon already has.
+                        // In general, Pokémon with lower friendship receive more,
+                        // and Pokémon with higher friendship receive less.
+                        if (GetMonData(mon, MON_DATA_FRIENDSHIP, NULL) < 100)
                         {
-                            var_34 = itemEffect[var_3C];
-                            friendship = GetMonData(mon, MON_DATA_FRIENDSHIP, NULL);
-                            if (var_34 > 0 && holdEffect == HOLD_EFFECT_HAPPINESS_UP)
-                                friendship += 150 * var_34 / 100;
-                            else
-                                friendship += var_34;
-                            if (var_34 > 0)
-                            {
-                                if (GetMonData(mon, MON_DATA_POKEBALL, NULL) == ITEM_LUXURY_BALL)
-                                    friendship++;
-                                if (GetMonData(mon, MON_DATA_MET_LOCATION, NULL) == GetCurrentRegionMapSectionId())
-                                    friendship++;
-                            }
-                            if (friendship < 0)
-                                friendship = 0;
-                            if (friendship > MAX_FRIENDSHIP)
-                                friendship = MAX_FRIENDSHIP;
-                            SetMonData(mon, MON_DATA_FRIENDSHIP, &friendship);
-                            retVal = FALSE;
+                            UPDATE_FRIENDSHIP_FROM_ITEM;
                         }
-                        var_3C++;
+                        itemEffectParam++;
                         break;
-                    case 6:
-                        if (GetMonData(mon, MON_DATA_FRIENDSHIP, NULL) >= 100 && GetMonData(mon, MON_DATA_FRIENDSHIP, NULL) < 200
-                         && (retVal == 0 || var_28 != 0) && !ShouldSkipFriendshipChange() && var_34 == 0)
+
+                    case 6: // ITEM5_FRIENDSHIP_MID
+                        if (GetMonData(mon, MON_DATA_FRIENDSHIP, NULL) >= 100 && GetMonData(mon, MON_DATA_FRIENDSHIP, NULL) < 200)
                         {
-                            var_34 = itemEffect[var_3C];
-                            friendship = GetMonData(mon, MON_DATA_FRIENDSHIP, NULL);
-                            if ((s8)(var_34) > 0 && holdEffect == HOLD_EFFECT_HAPPINESS_UP)
-                                friendship += 150 * var_34 / 100;
-                            else
-                                friendship += var_34;
-                            if (var_34 > 0)
-                            {
-                                if (GetMonData(mon, MON_DATA_POKEBALL, NULL) == ITEM_LUXURY_BALL)
-                                    friendship++;
-                                if (GetMonData(mon, MON_DATA_MET_LOCATION, NULL) == GetCurrentRegionMapSectionId())
-                                    friendship++;
-                            }
-                            if (friendship < 0)
-                                friendship = 0;
-                            if (friendship > MAX_FRIENDSHIP)
-                                friendship = MAX_FRIENDSHIP;
-                            SetMonData(mon, MON_DATA_FRIENDSHIP, &friendship);
-                            retVal = FALSE;
+                            UPDATE_FRIENDSHIP_FROM_ITEM;
                         }
-                        var_3C++;
+                        itemEffectParam++;
                         break;
-                    case 7:
-                        if (GetMonData(mon, MON_DATA_FRIENDSHIP, NULL) >= 200 && (retVal == 0 || var_28 != 0) && !ShouldSkipFriendshipChange() && var_34 == 0)
+
+                    case 7: // ITEM5_FRIENDSHIP_HIGH
+                        if (GetMonData(mon, MON_DATA_FRIENDSHIP, NULL) >= 200)
                         {
-                            var_34 = itemEffect[var_3C];
-                            friendship = GetMonData(mon, MON_DATA_FRIENDSHIP, NULL);
-                            if ((s8)(var_34) > 0 && holdEffect == HOLD_EFFECT_HAPPINESS_UP)
-                                friendship += 150 * var_34 / 100;
-                            else
-                                friendship += var_34;
-                            if (var_34 > 0)
-                            {
-                                if (GetMonData(mon, MON_DATA_POKEBALL, NULL) == ITEM_LUXURY_BALL)
-                                    friendship++;
-                                if (GetMonData(mon, MON_DATA_MET_LOCATION, NULL) == GetCurrentRegionMapSectionId())
-                                    friendship++;
-                            }
-                            if (friendship < 0)
-                                friendship = 0;
-                            if (friendship > MAX_FRIENDSHIP)
-                                friendship = MAX_FRIENDSHIP;
-                            SetMonData(mon, MON_DATA_FRIENDSHIP, &friendship);
-                            retVal = FALSE;
+                            UPDATE_FRIENDSHIP_FROM_ITEM;
                         }
-                        var_3C++;
+                        itemEffectParam++;
                         break;
                     }
                 }
-                var_38++;
-                r10 >>= 1;
+                temp1++;
+                effectFlags >>= 1;
             }
             break;
         }
@@ -5216,9 +5254,9 @@ u8 GetItemEffectParamOffset(u16 itemId, u8 effectByte, u8 effectBit)
     u8 offset;
     int i;
     u8 j;
-    u8 val;
+    u8 effectFlags;
 
-    offset = 6;
+    offset = ITEM_EFFECT_ARG_START;
 
     temp = gItemEffectTable[itemId - ITEM_POTION];
 
@@ -5232,7 +5270,7 @@ u8 GetItemEffectParamOffset(u16 itemId, u8 effectByte, u8 effectBit)
 
     itemEffect = temp;
 
-    for (i = 0; i < 6; i++)
+    for (i = 0; i < ITEM_EFFECT_ARG_START; i++)
     {
         switch (i)
         {
@@ -5244,74 +5282,75 @@ u8 GetItemEffectParamOffset(u16 itemId, u8 effectByte, u8 effectBit)
                 return 0;
             break;
         case 4:
-            val = itemEffect[4];
-            if (val & ITEM4_PP_UP)
-                val &= ~(ITEM4_PP_UP);
+            effectFlags = itemEffect[4];
+            if (effectFlags & ITEM4_PP_UP)
+                effectFlags &= ~(ITEM4_PP_UP);
             j = 0;
-            while (val)
+            while (effectFlags)
             {
-                if (val & 1)
+                if (effectFlags & 1)
                 {
                     switch (j)
                     {
-                    case 2:
-                        if (val & 0x10)
-                            val &= 0xEF;
-                    case 0:
-                        if (i == effectByte && (val & effectBit))
+                    case 2: // ITEM4_HEAL_HP
+                        if (effectFlags & (ITEM4_REVIVE >> 2))
+                            effectFlags &= ~(ITEM4_REVIVE >> 2);
+                        // fallthrough
+                    case 0: // ITEM4_EV_HP
+                        if (i == effectByte && (effectFlags & effectBit))
                             return offset;
                         offset++;
                         break;
-                    case 1:
-                        if (i == effectByte && (val & effectBit))
+                    case 1: // ITEM4_EV_ATK
+                        if (i == effectByte && (effectFlags & effectBit))
                             return offset;
                         offset++;
                         break;
-                    case 3:
-                        if (i == effectByte && (val & effectBit))
+                    case 3: // ITEM4_HEAL_PP
+                        if (i == effectByte && (effectFlags & effectBit))
                             return offset;
                         offset++;
                         break;
-                    case 7:
+                    case 7: // ITEM4_EVO_STONE
                         if (i == effectByte)
                             return 0;
                         break;
                     }
                 }
                 j++;
-                val >>= 1;
+                effectFlags >>= 1;
                 if (i == effectByte)
                     effectBit >>= 1;
             }
             break;
         case 5:
-            val = itemEffect[5];
+            effectFlags = itemEffect[5];
             j = 0;
-            while (val)
+            while (effectFlags)
             {
-                if (val & 1)
+                if (effectFlags & 1)
                 {
                     switch (j)
                     {
-                    case 0:
-                    case 1:
-                    case 2:
-                    case 3:
-                    case 4:
-                    case 5:
-                    case 6:
-                        if (i == effectByte && (val & effectBit))
+                    case 0: // ITEM5_EV_DEF
+                    case 1: // ITEM5_EV_SPEED
+                    case 2: // ITEM5_EV_SPDEF
+                    case 3: // ITEM5_EV_SPATK
+                    case 4: // ITEM5_PP_MAX
+                    case 5: // ITEM5_FRIENDSHIP_LOW
+                    case 6: // ITEM5_FRIENDSHIP_MID
+                        if (i == effectByte && (effectFlags & effectBit))
                             return offset;
                         offset++;
                         break;
-                    case 7:
+                    case 7: // ITEM5_FRIENDSHIP_HIGH
                         if (i == effectByte)
                             return 0;
                         break;
                     }
                 }
                 j++;
-                val >>= 1;
+                effectFlags >>= 1;
                 if (i == effectByte)
                     effectBit >>= 1;
             }
@@ -5387,7 +5426,7 @@ u8 GetNatureFromPersonality(u32 personality)
     return personality % NUM_NATURES;
 }
 
-u16 GetEvolutionTargetSpecies(struct Pokemon *mon, u8 type, u16 evolutionItem)
+u16 GetEvolutionTargetSpecies(struct Pokemon *mon, u8 mode, u16 evolutionItem)
 {
     int i;
     u16 targetSpecies = 0;
@@ -5405,12 +5444,13 @@ u16 GetEvolutionTargetSpecies(struct Pokemon *mon, u8 type, u16 evolutionItem)
     else
         holdEffect = ItemId_GetHoldEffect(heldItem);
 
-    if (holdEffect == HOLD_EFFECT_PREVENT_EVOLVE && type != 3)
+    // Prevent evolution with Everstone, unless we're just viewing the party menu with an evolution item
+    if (holdEffect == HOLD_EFFECT_PREVENT_EVOLVE && mode != EVO_MODE_ITEM_CHECK)
         return SPECIES_NONE;
 
-    switch (type)
+    switch (mode)
     {
-    case 0:
+    case EVO_MODE_NORMAL:
         level = GetMonData(mon, MON_DATA_LEVEL, 0);
         friendship = GetMonData(mon, MON_DATA_FRIENDSHIP, 0);
 
@@ -5470,7 +5510,7 @@ u16 GetEvolutionTargetSpecies(struct Pokemon *mon, u8 type, u16 evolutionItem)
             }
         }
         break;
-    case 1:
+    case EVO_MODE_TRADE:
         for (i = 0; i < EVOS_PER_MON; i++)
         {
             switch (gEvolutionTable[species][i].method)
@@ -5489,8 +5529,8 @@ u16 GetEvolutionTargetSpecies(struct Pokemon *mon, u8 type, u16 evolutionItem)
             }
         }
         break;
-    case 2:
-    case 3:
+    case EVO_MODE_ITEM_USE:
+    case EVO_MODE_ITEM_CHECK:
         for (i = 0; i < EVOS_PER_MON; i++)
         {
             if (gEvolutionTable[species][i].method == EVO_ITEM
diff --git a/src/trade.c b/src/trade.c
index afefce93c..efc499209 100644
--- a/src/trade.c
+++ b/src/trade.c
@@ -3735,7 +3735,7 @@ static bool8 AnimateTradeSequenceCable(void)
     case 72: // Only if in-game trade
         TradeMons(gSpecialVar_0x8005, 0);
         gCB2_AfterEvolution = CB2_UpdateInGameTrade;
-        evoTarget = GetEvolutionTargetSpecies(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], TRUE, ITEM_NONE);
+        evoTarget = GetEvolutionTargetSpecies(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], EVO_MODE_TRADE, ITEM_NONE);
         if (evoTarget != SPECIES_NONE)
         {
             TradeEvolutionScene(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], evoTarget, sTradeData->pokePicSpriteIdxs[TRADE_PARTNER], gSelectedTradeMonPositions[TRADE_PLAYER]);
@@ -4250,7 +4250,7 @@ static bool8 AnimateTradeSequenceWireless(void)
     case 72: // Only if in-game trade
         TradeMons(gSpecialVar_0x8005, 0);
         gCB2_AfterEvolution = CB2_UpdateInGameTrade;
-        evoTarget = GetEvolutionTargetSpecies(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], TRUE, ITEM_NONE);
+        evoTarget = GetEvolutionTargetSpecies(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], EVO_MODE_TRADE, ITEM_NONE);
         if (evoTarget != SPECIES_NONE)
         {
             TradeEvolutionScene(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], evoTarget, sTradeData->pokePicSpriteIdxs[TRADE_PARTNER], gSelectedTradeMonPositions[TRADE_PLAYER]);
@@ -4293,7 +4293,7 @@ static void CB2_TryTradeEvolution(void)
         break;
     case 4:
         gCB2_AfterEvolution = CB2_SaveAndEndTrade;
-        evoTarget = GetEvolutionTargetSpecies(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], TRUE, ITEM_NONE);
+        evoTarget = GetEvolutionTargetSpecies(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], EVO_MODE_TRADE, ITEM_NONE);
         if (evoTarget != SPECIES_NONE)
             TradeEvolutionScene(&gPlayerParty[gSelectedTradeMonPositions[TRADE_PLAYER]], evoTarget, sTradeData->pokePicSpriteIdxs[TRADE_PARTNER], gSelectedTradeMonPositions[TRADE_PLAYER]);
         else if (IsWirelessTrade())