Merge branch 'master' of github.com:pret/pokeyellow

26 files changed, 586 insertions, 442 deletions

diff --git a/engine/bank3c.asm b/engine/bank3c.asm
index 3683f2b1..d3bcc897 100644
--- a/engine/bank3c.asm
+++ b/engine/bank3c.asm
@@ -65,12 +65,12 @@ SetMapSpecificScriptFlagsOnMapReload: ; f02da (3c:42da)
 	ret
 
 .verm_gym
-	ld hl, wd126
+	ld hl, wCurrentMapScriptFlags
 	set 6, [hl]
 	ret
 
 .in_list
-	ld hl, wd126
+	ld hl, wCurrentMapScriptFlags
 	set 5, [hl]
 	ret
 
diff --git a/engine/bank3d.asm b/engine/bank3d.asm
index bf84e096..fbf816b6 100644
--- a/engine/bank3d.asm
+++ b/engine/bank3d.asm
@@ -456,12 +456,15 @@ Text_f5b28: ; f5b28 (3d:5b28)
 	TX_FAR _CanMoveBouldersText ; 2d:4193
 	db "@"
 
-CheckForForcedBikeSurf: ; f5b2d (3d:5b2d)
+IsSurfingAllowed: ; f5b2d (3d:5b2d)
+; Returns whether surfing is allowed in bit 1 of wd728.
+; Surfing isn't allowed on the Cycling Road or in the lowest level of the
+; Seafoam Islands before the current has been slowed with boulders.
 	ld hl, wd728
 	set 1, [hl]
 	ld a, [wd732]
 	bit 5, a
-	jr nz, .asm_f5b59
+	jr nz, .forcedToRideBike
 	ld a, [wCurMap]
 	cp SEAFOAM_ISLANDS_5
 	ret nz
@@ -474,7 +477,7 @@ CheckForForcedBikeSurf: ; f5b2d (3d:5b2d)
 	res 1, [hl]
 	ld hl, CurrentTooFastText
 	jp PrintText
-.asm_f5b59
+.forcedToRideBike
 	ld hl, wd728
 	res 1, [hl]
 	ld hl, CyclingIsFunText
@@ -499,7 +502,7 @@ AddItemToInventory_: ; f5b70 (3d:5b70)
 	push de
 	push hl
 	push hl
-	ld d, 50 ; PC box can hold 50 items
+	ld d, PC_ITEM_CAPACITY ; how many items the PC can hold
 	ld a, wNumBagItems & $FF
 	cp l
 	jr nz, .checkIfInventoryFull
@@ -507,7 +510,7 @@ AddItemToInventory_: ; f5b70 (3d:5b70)
 	cp h
 	jr nz, .checkIfInventoryFull
 ; if the destination is the bag
-	ld d, 20 ; bag can hold 20 items
+	ld d, BAG_ITEM_CAPACITY ; how many items the bag can hold
 .checkIfInventoryFull
 	ld a, [hl]
 	sub d
diff --git a/engine/battle/common_text.asm b/engine/battle/common_text.asm
index 0ca9ce96..a0c44346 100644
--- a/engine/battle/common_text.asm
+++ b/engine/battle/common_text.asm
@@ -9,8 +9,8 @@ PrintBeginningBattleText: ; f4000 (3d:4000)
 	jr c, .pokemonTower
 .notPokemonTower
 	ld a,[wBattleType]
-	cp $4 ; new battle type?
-	jr nz,.notnewbattletype
+	cp BATTLE_TYPE_PIKACHU
+	jr nz,.notPikachuBattle
 	callab IsPlayerPikachuAsleepInParty
 	ld e,$24
 	jr c,.asm_f4026
@@ -18,7 +18,7 @@ PrintBeginningBattleText: ; f4000 (3d:4000)
 .asm_f4026
 	callab PlayPikachuSoundClip
 	jr .continue
-.notnewbattletype
+.notPikachuBattle
 	ld a, [wEnemyMonSpecies2]
 	call PlayCry
 .continue
diff --git a/engine/battle/core.asm b/engine/battle/core.asm
index 565525ea..24b3863b 100755
--- a/engine/battle/core.asm
+++ b/engine/battle/core.asm
@@ -250,9 +250,9 @@ StartBattle: ; 3c127 (f:4127)
 	call SaveScreenTilesToBuffer1
 .checkAnyPartyAlive
 	ld a, [wBattleType]
-	cp $3
+	cp BATTLE_TYPE_RUN
 	jp z, .specialBattle
-	cp $4
+	cp BATTLE_TYPE_PIKACHU
 	jp z, .specialBattle
 	call AnyPartyAlive
 	ld a, d
@@ -1625,9 +1625,9 @@ TryRunningFromBattle: ; 3cb1e (f:4b1e)
 	call IsGhostBattle
 	jp z, .canEscape ; jump if it's a ghost battle
 	ld a, [wBattleType]
-	cp $2
+	cp BATTLE_TYPE_SAFARI
 	jp z, .canEscape ; jump if it's a safari battle
-	cp $3
+	cp BATTLE_TYPE_RUN
 	jp z, .canEscape ; hurry, get away?
 	ld a, [wLinkState]
 	cp LINK_STATE_BATTLING
@@ -1770,7 +1770,7 @@ LoadBattleMonFromParty: ; 3cc10 (f:4c10)
 	ld bc, NUM_MOVES
 	call CopyData
 	ld de, wBattleMonLevel
-	ld bc, $b
+	ld bc, wBattleMonPP - wBattleMonLevel
 	call CopyData
 	ld a, [wBattleMonSpecies2]
 	ld [wd0b5], a
@@ -1814,7 +1814,7 @@ LoadEnemyMonFromParty: ; 3cc7d (f:4c7d)
 	ld bc, NUM_MOVES
 	call CopyData
 	ld de, wEnemyMonLevel
-	ld bc, $b
+	ld bc, wEnemyMonPP - wEnemyMonLevel
 	call CopyData
 	ld a, [wEnemyMonSpecies]
 	ld [wd0b5], a
@@ -1990,11 +1990,11 @@ DrawPlayerHUDAndHPBar: ; 3ce25 (f:4e25)
 	call PlaceString
 	ld hl, wBattleMonSpecies
 	ld de, wLoadedMon
-	ld bc, $c
+	ld bc, wBattleMonDVs - wBattleMonSpecies
 	call CopyData
 	ld hl, wBattleMonLevel
 	ld de, wLoadedMonLevel
-	ld bc, $b
+	ld bc, wBattleMonPP - wBattleMonLevel
 	call CopyData
 	coord hl, 14, 8
 	push hl
@@ -2171,7 +2171,7 @@ DisplayBattleMenu: ; 3cf78 (f:4f78)
 	call SaveScreenTilesToBuffer1
 .nonstandardbattle
 	ld a, [wBattleType]
-	cp $2 ; safari
+	cp BATTLE_TYPE_SAFARI
 	ld a, BATTLE_MENU_TEMPLATE
 	jr nz, .menuselected
 	ld a, SAFARI_BATTLE_MENU_TEMPLATE
@@ -2179,9 +2179,9 @@ DisplayBattleMenu: ; 3cf78 (f:4f78)
 	ld [wTextBoxID], a
 	call DisplayTextBoxID
 	ld a, [wBattleType]
-	cp $1
+	cp BATTLE_TYPE_OLD_MAN
 	jr z, .doSimulatedMenuInput ; simulate menu input if it's the old man or prof. oak pikachu battle
-	cp $4
+	cp BATTLE_TYPE_PIKACHU
 	jr z, .doSimulatedMenuInput
 	jp .handleBattleMenuInput
 ; the following happens for the old man tutorial and prof. oak pikachu battle
@@ -2234,7 +2234,7 @@ DisplayBattleMenu: ; 3cf78 (f:4f78)
 	jr .rightColumn
 .leftColumn ; put cursor in left column of menu
 	ld a, [wBattleType]
-	cp $2
+	cp BATTLE_TYPE_SAFARI
 	ld a, " "
 	jr z, .safariLeftColumn
 ; put cursor in left column for normal battle menu (i.e. when it's not a Safari battle)
@@ -2267,7 +2267,7 @@ DisplayBattleMenu: ; 3cf78 (f:4f78)
 	jr .AButtonPressed ; the A button was pressed
 .rightColumn ; put cursor in right column of menu
 	ld a, [wBattleType]
-	cp $2
+	cp BATTLE_TYPE_SAFARI
 	ld a, " "
 	jr z, .safariRightColumn
 ; put cursor in right column for normal battle menu (i.e. when it's not a Safari battle)
@@ -2304,10 +2304,10 @@ DisplayBattleMenu: ; 3cf78 (f:4f78)
 .AButtonPressed
 	call PlaceUnfilledArrowMenuCursor
 	ld a, [wBattleType]
-	cp HURRY_RUN_AWAY_BATTLE
+	cp BATTLE_TYPE_RUN
 	jr z, .handleUnusedBattle
 	ld a, [wBattleType]
-	cp SAFARI_BATTLE ; is it a Safari battle?
+	cp BATTLE_TYPE_SAFARI
 	ld a, [wCurrentMenuItem]
 	ld [wBattleAndStartSavedMenuItem], a
 	jr z, .handleMenuSelection
@@ -2329,7 +2329,7 @@ DisplayBattleMenu: ; 3cf78 (f:4f78)
 	jr nz, .upperLeftMenuItemWasNotSelected
 ; the upper left menu item was selected
 	ld a, [wBattleType]
-	cp $2
+	cp BATTLE_TYPE_SAFARI
 	jr z, .throwSafariBallWasSelected
 ; the "FIGHT" menu was selected
 	xor a
@@ -2368,7 +2368,7 @@ DisplayBattleMenu: ; 3cf78 (f:4f78)
 .notLinkBattle
 	call SaveScreenTilesToBuffer2
 	ld a, [wBattleType]
-	cp $2 ; is it a safari battle?
+	cp BATTLE_TYPE_SAFARI
 	jr nz, BagWasSelected
 
 ; bait was selected
@@ -2386,9 +2386,9 @@ BagWasSelected: ; 3d10a (f:510a)
 	call DrawHUDsAndHPBars
 .next
 	ld a, [wBattleType]
-	cp OLD_MAN_BATTLE ; is it the old man tutorial?
+	cp BATTLE_TYPE_OLD_MAN ; is it the old man tutorial?
 	jr z, .simulatedInputBattle
-	cp STARTER_PIKACHU_BATTLE ; is it the prof oak battle with pikachu?
+	cp BATTLE_TYPE_PIKACHU ; is it the prof oak battle with pikachu?
 	jr z, .simulatedInputBattle
 	jr DisplayPlayerBag
 .simulatedInputBattle
@@ -2441,7 +2441,7 @@ UseBagItem: ; 3c162 (f:5162)
 	xor a
 	ld [wCurrentMenuItem], a
 	ld a, [wBattleType]
-	cp SAFARI_BATTLE ; is it a safari battle?
+	cp BATTLE_TYPE_SAFARI
 	jr z, .checkIfMonCaptured
 
 	ld a, [wActionResultOrTookBattleTurn]
@@ -2463,7 +2463,7 @@ UseBagItem: ; 3c162 (f:5162)
 	jr nz, .returnAfterCapturingMon
 
 	ld a, [wBattleType]
-	cp SAFARI_BATTLE ; is it a safari battle?
+	cp BATTLE_TYPE_SAFARI
 	jr z, .returnAfterUsingItem_NoCapture
 ; not a safari battle
 	call LoadScreenTilesFromBuffer1
@@ -2494,7 +2494,7 @@ PartyMenuOrRockOrRun: ; 3d1cd (f:51cd)
 ; party menu or rock was selected
 	call SaveScreenTilesToBuffer2
 	ld a, [wBattleType]
-	cp $2 ; is it a safari battle?
+	cp BATTLE_TYPE_SAFARI
 	jr nz, .partyMenuWasSelected
 ; safari battle
 	ld a, SAFARI_ROCK
@@ -3626,7 +3626,7 @@ CheckPlayerStatusConditions: ; 3d9c6 (f:59c6)
 	ld a,[wPlayerBattleStatus1]
 	add a ; is player confused?
 	jr nc,.TriedToUseDisabledMoveCheck
-	ld hl,W_PLAYERCONFUSEDCOUNTER
+	ld hl,wPlayerConfusedCounter
 	dec [hl]
 	jr nz,.IsConfused
 	ld hl,wPlayerBattleStatus1
@@ -3764,7 +3764,7 @@ CheckPlayerStatusConditions: ; 3d9c6 (f:59c6)
 	and a,3
 	inc a
 	inc a ; confused for 2-5 turns
-	ld [W_PLAYERCONFUSEDCOUNTER],a
+	ld [wPlayerConfusedCounter],a
 	pop hl ; skip DecrementPP
 	jp .returnToHL
 
@@ -6126,7 +6126,7 @@ CheckEnemyStatusConditions: ; 3ea15 (f:6a15)
 	ld a, [wEnemyBattleStatus1]
 	add a ; check if enemy mon is confused
 	jp nc, .checkIfTriedToUseDisabledMove
-	ld hl, W_ENEMYCONFUSEDCOUNTER
+	ld hl, wEnemyConfusedCounter
 	dec [hl]
 	jr nz, .isConfused
 	ld hl, wEnemyBattleStatus1
@@ -6298,7 +6298,7 @@ CheckEnemyStatusConditions: ; 3ea15 (f:6a15)
 	and $3
 	inc a
 	inc a ; confused for 2-5 turns
-	ld [W_ENEMYCONFUSEDCOUNTER], a
+	ld [wEnemyConfusedCounter], a
 	pop hl ; skip DecrementPP
 	jp .enemyReturnToHL
 .checkIfUsingMultiturnMove
@@ -6576,10 +6576,10 @@ SwapPlayerAndEnemyLevels: ; 3ee07 (f:6e07)
 LoadPlayerBackPic: ; 3ee18 (f:6e18)
 	ld a, [wBattleType]
 	ld de, OldManPic
-	cp OLD_MAN_BATTLE ; is it the old man tutorial?
+	cp BATTLE_TYPE_OLD_MAN ; is it the old man tutorial?
 	jr z, .next
 	ld de, ProfOakPicBack
-	cp STARTER_PIKACHU_BATTLE ; is it the pikachu battle at the beginning of the game?
+	cp BATTLE_TYPE_PIKACHU ; is it the pikachu battle at the beginning of the game?
 	jr z, .next
 	ld de, RedPicBack
 .next
@@ -6624,7 +6624,7 @@ LoadPlayerBackPic: ; 3ee18 (f:6e18)
 	ld a, $0
 	call SwitchSRAMBankAndLatchClockData
 	ld hl, vSprites
-	ld de, S_SPRITEBUFFER1
+	ld de, sSpriteBuffer1
 	ld a, [H_LOADEDROMBANK]
 	ld b, a
 	ld c, 7 * 7
@@ -8292,11 +8292,11 @@ ConfusionSideEffectSuccess: ; 3f94a (f:794a)
 	ld a, [H_WHOSETURN]
 	and a
 	ld hl, wEnemyBattleStatus1
-	ld bc, W_ENEMYCONFUSEDCOUNTER
+	ld bc, wEnemyConfusedCounter
 	ld a, [wPlayerMoveEffect]
 	jr z, .confuseTarget
 	ld hl, wPlayerBattleStatus1
-	ld bc, W_PLAYERCONFUSEDCOUNTER
+	ld bc, wPlayerConfusedCounter
 	ld a, [wEnemyMoveEffect]
 .confuseTarget
 	bit Confused, [hl] ; is mon confused?
diff --git a/engine/battle/init_battle_variables.asm b/engine/battle/init_battle_variables.asm
index 8c43e8f8..74ea3814 100644
--- a/engine/battle/init_battle_variables.asm
+++ b/engine/battle/init_battle_variables.asm
@@ -32,7 +32,7 @@ InitBattleVariables: ; f6236 (3d:6236)
 	jr c, .notSafariBattle
 	cp SAFARI_ZONE_REST_HOUSE_1
 	jr nc, .notSafariBattle
-	ld a, $2 ; safari battle
+	ld a, BATTLE_TYPE_SAFARI
 	ld [wBattleType], a
 .notSafariBattle
 	jpab PlayBattleMusic
diff --git a/engine/battle/moveEffects/pay_day_effect.asm b/engine/battle/moveEffects/pay_day_effect.asm
index 2fa6b53f..0236e3e4 100644
--- a/engine/battle/moveEffects/pay_day_effect.asm
+++ b/engine/battle/moveEffects/pay_day_effect.asm
@@ -1,4 +1,4 @@
-PayDayEffect_ ; f6511 (3d:6511)
+PayDayEffect_: ; f6511 (3d:6511)
 	xor a
 	ld hl, wcd6d
 	ld [hli], a
diff --git a/engine/battle/scale_sprites.asm b/engine/battle/scale_sprites.asm
index 03495c82..c829fa13 100644
--- a/engine/battle/scale_sprites.asm
+++ b/engine/battle/scale_sprites.asm
@@ -9,12 +9,12 @@ ScaleSpriteByTwo: ; 2fd79 (b:7d79)
 	ret
 
 ScaleSpriteByTwo_: ; 2fd85 (b:7d85)
-	ld de, S_SPRITEBUFFER1 + (4*4*8) - 5          ; last byte of input data, last 4 rows already skipped
-	ld hl, S_SPRITEBUFFER0 + SPRITEBUFFERSIZE - 1 ; end of destination buffer
+	ld de, sSpriteBuffer1 + (4*4*8) - 5          ; last byte of input data, last 4 rows already skipped
+	ld hl, sSpriteBuffer0 + SPRITEBUFFERSIZE - 1 ; end of destination buffer
 	call ScaleLastSpriteColumnByTwo               ; last tile column is special case
 	call ScaleFirstThreeSpriteColumnsByTwo        ; scale first 3 tile columns
-	ld de, S_SPRITEBUFFER2 + (4*4*8) - 5          ; last byte of input data, last 4 rows already skipped
-	ld hl, S_SPRITEBUFFER1 + SPRITEBUFFERSIZE - 1 ; end of destination buffer
+	ld de, sSpriteBuffer2 + (4*4*8) - 5          ; last byte of input data, last 4 rows already skipped
+	ld hl, sSpriteBuffer1 + SPRITEBUFFERSIZE - 1 ; end of destination buffer
 	call ScaleLastSpriteColumnByTwo               ; last tile column is special case
 
 ScaleFirstThreeSpriteColumnsByTwo: ; 2fd9a (b:7d9a)
diff --git a/engine/diploma_3a.asm b/engine/diploma_3a.asm
index 520d9f96..f85cc288 100755
--- a/engine/diploma_3a.asm
+++ b/engine/diploma_3a.asm
@@ -91,12 +91,12 @@ Func_e9ad3:
 	coord hl, 2, 15
 	call PlaceString
 	coord hl, 12, 15
-	ld de, wPlayTimeHours + 1
+	ld de, wPlayTimeHours
 	lb bc, $40 | 1, 3
 	call PrintNumber
 	ld [hl], $16
 	inc hl
-	ld de, wPlayTimeMinutes + 1
+	ld de, wPlayTimeMinutes
 	lb bc, $80 | 1, 2
 	call PrintNumber
 	ld a, [wNumSetBits]
diff --git a/engine/hall_of_fame.asm b/engine/hall_of_fame.asm
index ee138737..c8e6de3b 100755
--- a/engine/hall_of_fame.asm
+++ b/engine/hall_of_fame.asm
@@ -202,8 +202,8 @@ HoFLoadPlayerPics: ; 70390 (1c:433e)
 	call UncompressSpriteFromDE
 	ld a,$0
 	call SwitchSRAMBankAndLatchClockData
-	ld hl, S_SPRITEBUFFER1
-	ld de, S_SPRITEBUFFER0
+	ld hl, sSpriteBuffer1
+	ld de, sSpriteBuffer0
 	ld bc, $310
 	call CopyData
 	call PrepareRTCDataAndDisableSRAM
@@ -238,12 +238,12 @@ HoFDisplayPlayerStats: ; 703d1 (1c:43d1)
 	ld de, HoFPlayTimeText
 	call PlaceString
 	coord hl, 5, 7
-	ld de, wPlayTimeHours + 1
+	ld de, wPlayTimeHours
 	lb bc, 1, 3
 	call PrintNumber
 	ld [hl], $6d
 	inc hl
-	ld de, wPlayTimeMinutes + 1
+	ld de, wPlayTimeMinutes
 	lb bc, LEADING_ZEROES | 1, 2
 	call PrintNumber
 	coord hl, 1, 9
diff --git a/engine/hidden_object_functions17.asm b/engine/hidden_object_functions17.asm
index 58838434..7753cad1 100755
--- a/engine/hidden_object_functions17.asm
+++ b/engine/hidden_object_functions17.asm
@@ -1,4 +1,4 @@
-PrintRedsNESText: ; 5dbae (17:5bae)
+PrintRedSNESText: ; 5dbae (17:5bae)
 	call EnableAutoTextBoxDrawing
 	tx_pre_jump RedBedroomSNESText
 
@@ -11,7 +11,7 @@ OpenRedsPC: ; 5db86 (17:5b86)
 	tx_pre_jump RedBedroomPCText
 
 RedBedroomPCText: ; 5db8e (17:5b8e)
-	db $fc ; FuncTX_ItemStoragePC
+	TX_PLAYERS_PC
 
 Route15GateLeftBinoculars: ; 5db8f (17:5b8f)
 	ld a, [wPlayerFacingDirection]
@@ -122,7 +122,7 @@ LinkCableHelp: ; 5dc29 (17:5c29)
 	ld hl, LinkCableHelpText1
 	call PrintText
 	xor a
-	ld [wAnimationID], a
+	ld [wMenuItemOffset], a
 	ld [wCurrentMenuItem], a
 	ld [wLastMenuItem], a
 	ld a, A_BUTTON | B_BUTTON
@@ -205,7 +205,7 @@ ViridianSchoolBlackboard: ; 5dced (17:5ced)
 	ld hl, ViridianSchoolBlackboardText1
 	call PrintText
 	xor a
-	ld [wAnimationID], a
+	ld [wMenuItemOffset], a
 	ld [wCurrentMenuItem], a
 	ld [wLastMenuItem], a
 	ld a, D_LEFT | D_RIGHT | A_BUTTON | B_BUTTON
@@ -242,8 +242,8 @@ ViridianSchoolBlackboard: ; 5dced (17:5ced)
 	ld [wTopMenuItemY], a
 	ld a, $6
 	ld [wTopMenuItemX], a
-	ld a, $3
-	ld [wAnimationID], a
+	ld a, $3 ; in the the right column, use an offset to prevent overlap
+	ld [wMenuItemOffset], a
 	jr .blackboardLoop
 .didNotPressRight
 	bit 5, a ; pressed left
@@ -256,7 +256,7 @@ ViridianSchoolBlackboard: ; 5dced (17:5ced)
 	ld a, $1
 	ld [wTopMenuItemX], a
 	xor a
-	ld [wAnimationID], a
+	ld [wMenuItemOffset], a
 	jr .blackboardLoop
 .didNotPressLeftOrRight
 	ld a, [wCurrentMenuItem]
@@ -306,7 +306,7 @@ StatusAilmentText2: ; 5ddbb (17:5dbb)
 ViridianBlackboardStatusPointers: ; 5ddcc (17:5ddc)
 	dw ViridianBlackboardSleepText
 	dw ViridianBlackboardPoisonText
-	dw ViridianBlackbaordPrlzText
+	dw ViridianBlackboardPrlzText
 	dw ViridianBlackboardBurnText
 	dw ViridianBlackboardFrozenText
 
@@ -318,8 +318,8 @@ ViridianBlackboardPoisonText: ; 5dddb (17:5ddb)
 	TX_FAR _ViridianBlackboardPoisonText
 	db "@"
 
-ViridianBlackbaordPrlzText: ; 5dde0 (17:5de0)
-	TX_FAR _ViridianBlackbaordPrlzText
+ViridianBlackboardPrlzText: ; 5dde0 (17:5de0)
+	TX_FAR _ViridianBlackboardPrlzText
 	db "@"
 
 ViridianBlackboardBurnText: ; 5dde5 (17:5de5)
@@ -366,7 +366,7 @@ GymTrashScript: ; 5ddfc (17:5dfc)
 ; Next can is trying for the second switch.
 	SetEvent EVENT_1ST_LOCK_OPENED
 	callab Yellow_SampleSecondTrashCan
-	tx_pre_id VermilionGymTrashSuccesText1
+	tx_pre_id VermilionGymTrashSuccessText1
 	jr .done
 
 .trySecondLock
@@ -392,10 +392,10 @@ GymTrashScript: ; 5ddfc (17:5dfc)
 .openSecondLock
 ; Completed the trash can puzzle.
 	SetEvent EVENT_2ND_LOCK_OPENED
-	ld hl, wd126
+	ld hl, wCurrentMapScriptFlags
 	set 6, [hl]
 
-	tx_pre_id VermilionGymTrashSuccesText3
+	tx_pre_id VermilionGymTrashSuccessText3
 
 .done
 	jp PrintPredefTextID
@@ -425,8 +425,8 @@ GymTrashCans: ; 5de7d (17:5e7d)
 	db 2, 11, 13, -1, -1 ; 14
 ; 5dec8
 
-VermilionGymTrashSuccesText1: ; 5dec8 (17:5ec8)
-	TX_FAR _VermilionGymTrashSuccesText1
+VermilionGymTrashSuccessText1: ; 5dec8 (17:5ec8)
+	TX_FAR _VermilionGymTrashSuccessText1
 	TX_ASM
 	call WaitForSoundToFinish
 	ld a, SFX_SWITCH
@@ -435,8 +435,8 @@ VermilionGymTrashSuccesText1: ; 5dec8 (17:5ec8)
 	jp TextScriptEnd
 
 ; unused
-VermilionGymTrashSuccesText2: ; 5dedb (17:5edb)
-	TX_FAR _VermilionGymTrashSuccesText2
+VermilionGymTrashSuccessText2: ; 5dedb (17:5edb)
+	TX_FAR _VermilionGymTrashSuccessText2
 	db "@"
 
 ; unused
@@ -448,8 +448,8 @@ VermilionGymTrashSuccesPlaySfx: ; 5dee0 (17:5ee0)
 	call WaitForSoundToFinish
 	jp TextScriptEnd
 
-VermilionGymTrashSuccesText3: ; 5deef (17:5eef)
-	TX_FAR _VermilionGymTrashSuccesText3
+VermilionGymTrashSuccessText3: ; 5deef (17:5eef)
+	TX_FAR _VermilionGymTrashSuccessText3
 	TX_ASM
 	call WaitForSoundToFinish
 	ld a, SFX_GO_INSIDE
diff --git a/engine/hidden_object_functions7.asm b/engine/hidden_object_functions7.asm
index 6e232664..4867b447 100755
--- a/engine/hidden_object_functions7.asm
+++ b/engine/hidden_object_functions7.asm
@@ -22,9 +22,10 @@ DisplayOakLabRightPoster: ; 1e2fe (7:62fe)
 	ld a, [wNumSetBits]
 	cp 2
 	tx_pre_id SaveOptionText
-	jr c, .ownOneMon
+	jr c, .ownLessThanTwo
+	; own two or more mon
 	tx_pre_id StrengthsAndWeaknessesText
-.ownOneMon
+.ownLessThanTwo
 	jp PrintPredefTextID
 
 SaveOptionText: ; 1e317 (7:6317)
@@ -209,7 +210,7 @@ CinnabarGymQuiz_1ea92: ; 1e43a (7:643a)
 	ld a, [wCurrentMenuItem]
 	cp c
 	jr nz, .wrongAnswer
-	ld hl, wd126
+	ld hl, wCurrentMapScriptFlags
 	set 5, [hl]
 	ld a, [hGymGateIndex]
 	ld [$ffe0], a
@@ -434,7 +435,7 @@ BillsHousePokemonList: ; 1e5dc (7:65dc)
 	ld hl, BillsHousePokemonListText1
 	call PrintText
 	xor a
-	ld [wAnimationID], a
+	ld [wMenuItemOffset], a
 	ld [wCurrentMenuItem], a
 	ld [wLastMenuItem], a
 	ld a, A_BUTTON | B_BUTTON
diff --git a/engine/items/items.asm b/engine/items/items.asm
index 96dd0a00..e3fe4655 100755
--- a/engine/items/items.asm
+++ b/engine/items/items.asm
@@ -101,240 +101,341 @@ ItemUsePtrTable: ; d307 (3:5307)
 	dw ItemUsePPRestore  ; MAX_ELIXER
 
 ItemUseBall: ; d3ad (3:53ad)
-	ld a, [wIsInBattle]
+
+; Balls can't be used out of battle.
+	ld a,[wIsInBattle]
 	and a
-	jp z, ItemUseNotTime ; not in battle
+	jp z,ItemUseNotTime
+
+; Balls can't catch trainers' Pokémon.
 	dec a
-	jp nz, ThrowBallAtTrainerMon
-	ld a, [wBattleType]
-	cp $1
-	jr z, .UseBall
-	cp $4 ; pikachu battle?
-	jr z, .UseBall
-	ld a, [wPartyCount]	;is Party full?
-	cp PARTY_LENGTH
-	jr nz, .UseBall
-	ld a, [wNumInBox]	;is Box full?
-	cp MONS_PER_BOX
-	jp z, BoxFullCannotThrowBall
-.UseBall
-;ok, you can use a ball
+	jp nz,ThrowBallAtTrainerMon
+
+; If this is for the old man battle, skip checking if the party & box are full.
+	ld a,[wBattleType]
+	cp BATTLE_TYPE_OLD_MAN
+	jr z,.canUseBall
+	cp BATTLE_TYPE_PIKACHU
+	jr z,.canUseBall
+
+	ld a,[wPartyCount] ; is party full?
+	cp a,PARTY_LENGTH
+	jr nz,.canUseBall
+	ld a,[wNumInBox] ; is box full?
+	cp a,MONS_PER_BOX
+	jp z,BoxFullCannotThrowBall
+
+.canUseBall
 	xor a
-	ld [wCapturedMonSpecies], a
-	ld a, [wBattleType]
-	cp 2		;SafariBattle
-	jr nz, .skipSafariZoneCode
+	ld [wCapturedMonSpecies],a
+
+	ld a,[wBattleType]
+	cp a,BATTLE_TYPE_SAFARI
+	jr nz,.skipSafariZoneCode
+
 .safariZone
-	; remove a Safari Ball from inventory
-	ld hl, wNumSafariBalls
-	dec [hl]
+	ld hl,wNumSafariBalls
+	dec [hl] ; remove a Safari Ball
+
 .skipSafariZoneCode
 	call RunDefaultPaletteCommand
-	ld a, $43
-	ld [wd11e], a
-	call LoadScreenTilesFromBuffer1	;restore screenBuffer from Backup
-	ld hl, ItemUseText00
+
+	ld a,$43 ; successful capture value
+	ld [wPokeBallAnimData],a
+
+	call LoadScreenTilesFromBuffer1
+	ld hl,ItemUseText00
 	call PrintText
+
+; If the player is fighting an unidentified ghost, set the value that indicates
+; the Pokémon can't be caught and skip the capture calculations.
 	callab IsGhostBattle
-	ld b, $10
-	jp z, .next12
-	ld a, [wBattleType]
-	cp $1
-	jr z, .oldManBattle
-	cp $4
-	jr z, .oldManBattle ; pikachu battle technically old man battle
+	ld b,$10 ; can't be caught value
+	jp z,.setAnimData
+
+	ld a,[wBattleType]
+	cp BATTLE_TYPE_OLD_MAN
+	jr z,.oldManBattle
+	cp BATTLE_TYPE_PIKACHU
+	jr z,.oldManBattle ; pikachu battle technically old man battle
 	jr .notOldManBattle
 
 .oldManBattle
-	ld hl, wGrassRate
-	ld de, wPlayerName
-	ld bc, NAME_LENGTH
-	call CopyData ; save the player's name in the Wild Monster data
+	ld hl,wGrassRate
+	ld de,wPlayerName
+	ld bc,NAME_LENGTH
+	call CopyData ; save the player's name in the Wild Monster data (part of the Cinnabar Island Missingno. glitch)
 	ld a, [wBattleType]
-	cp MASTER_BALL
-	jp nz, .BallSuccess
-	ld a, $1
+	cp BATTLE_TYPE_OLD_MAN
+	jp nz,.captured
+	ld a,$1
 	ld [wCapturedMonSpecies], a
 	CheckEvent EVENT_02F
 	ld b, $63
-	jp nz, .next12
-	jp .BallSuccess
-
+	jp nz,.setAnimData
+	jp .captured
 .notOldManBattle
-	ld a, [wCurMap]
-	cp POKEMONTOWER_6
-	jr nz, .loop
-	ld a, [wEnemyMonSpecies2]
-	cp MAROWAK
-	ld b, $10
-	jp z, .next12
-; if not fighting ghost Marowak, loop until a random number in the current
-; pokeball's allowed range is found
+; If the player is fighting the ghost Marowak, set the value that indicates the
+; Pokémon can't be caught and skip the capture calculations.
+	ld a,[wCurMap]
+	cp a,POKEMONTOWER_6
+	jr nz,.loop
+	ld a,[wEnemyMonSpecies2]
+	cp a,MAROWAK
+	ld b,$10 ; can't be caught value
+	jp z,.setAnimData
+
+; Get the first random number. Let it be called Rand1.
+; Rand1 must be within a certain range according the kind of ball being thrown.
+; The ranges are as follows.
+; Poké Ball:         [0, 255]
+; Great Ball:        [0, 200]
+; Ultra/Safari Ball: [0, 150]
+; Loop until an acceptable number is found.
+
 .loop
 	call Random
-	ld b, a
-	ld hl, wcf91
+	ld b,a
+
+; Get the item ID.
+	ld hl,wcf91
 .asm_d54a
-	ld a, [hl]
-	cp MASTER_BALL
-	jp z, .BallSuccess
-	cp POKE_BALL
-	jr z, .checkForAilments
-	ld a, 200
+	ld a,[hl]
+
+; The Master Ball always succeeds.
+	cp a,MASTER_BALL
+	jp z,.captured
+
+; Anything will do for the basic Poké Ball.
+	cp a,POKE_BALL
+	jr z,.checkForAilments
+
+; If it's a Great/Ultra/Safari Ball and Rand1 is greater than 200, try again.
+	ld a,200
 	cp b
-	jr c, .loop	;get only numbers <= 200 for Great Ball
-	ld a, [hl]
-	cp GREAT_BALL
-	jr z, .checkForAilments
-	ld a, 150	;get only numbers <= 150 for Ultra Ball
+	jr c,.loop
+
+; Less than or equal to 200 is good enough for a Great Ball.
+	ld a,[hl]
+	cp a,GREAT_BALL
+	jr z,.checkForAilments
+
+; If it's an Ultra/Safari Ball and Rand1 is greater than 150, try again.
+	ld a,150
 	cp b
-	jr c, .loop
+	jr c,.loop
+
 .checkForAilments
-; pokemon can be caught more easily with any (primary) status ailment
-; Frozen/Asleep pokemon are relatively even easier to catch
-; for Frozen/Asleep pokemon, any random number from 0-24 ensures a catch.
-; for the others, a random number from 0-11 ensures a catch.
-	ld a, [wEnemyMonStatus]	;status ailments
+; Pokémon can be caught more easily with a status ailment.
+; Depending on the status ailment, a certain value will be subtracted from
+; Rand1. Let this value be called Status.
+; The larger Status is, the more easily the Pokémon can be caught.
+; no status ailment:     Status = 0
+; Burn/Paralysis/Poison: Status = 12
+; Freeze/Sleep:          Status = 25
+; If Status is greater than Rand1, the Pokémon will be caught for sure.
+	ld a,[wEnemyMonStatus]
 	and a
-	jr z, .noAilments
-	and 1 << FRZ | SLP	;is frozen and/or asleep?
-	ld c, 12
-	jr z, .notFrozenOrAsleep
-	ld c, 25
+	jr z,.skipAilmentValueSubtraction ; no ailments
+	and a, 1 << FRZ | SLP
+	ld c,12
+	jr z,.notFrozenOrAsleep
+	ld c,25
 .notFrozenOrAsleep
 	ld a, b
 	sub c
-	jp c, .BallSuccess
-	ld b, a
-.noAilments
-	push bc		;save RANDOM number
+	jp c,.captured
+	ld b,a
+
+.skipAilmentValueSubtraction
+	push bc	; save (Rand1 - Status)
+
+; Calculate MaxHP * 255.
 	xor a
-	ld [H_MULTIPLICAND], a
-	ld hl, wEnemyMonMaxHP
-	ld a, [hli]
-	ld [H_MULTIPLICAND + 1], a
-	ld a, [hl]
-	ld [H_MULTIPLICAND + 2], a
-	ld a, 255
-	ld [H_MULTIPLIER], a
-	call Multiply	; MaxHP * 255
-	ld a, [wcf91]
+	ld [H_MULTIPLICAND],a
+	ld hl,wEnemyMonMaxHP
+	ld a,[hli]
+	ld [H_MULTIPLICAND + 1],a
+	ld a,[hl]
+	ld [H_MULTIPLICAND + 2],a
+	ld a,255
+	ld [H_MULTIPLIER],a
+	call Multiply
+
+; Determine BallFactor. It's 8 for Great Balls and 12 for the others.
+	ld a,[wcf91]
 	cp GREAT_BALL
-	ld a, 12		;any other BallFactor
-	jr nz, .next7
-	ld a, 8
-.next7
-	ld [H_DIVISOR], a
-	ld b, 4		; number of bytes in dividend
+	ld a,12
+	jr nz,.skip1
+	ld a,8
+
+.skip1
+; Note that the results of all division operations are floored.
+
+; Calculate (MaxHP * 255) / BallFactor.
+	ld [H_DIVISOR],a
+	ld b,4 ; number of bytes in dividend
 	call Divide
-	ld hl, wEnemyMonHP
-	ld a, [hli]
-	ld b, a
-	ld a, [hl]
 
-; explanation: we have a 16-bit value equal to [b << 8 | a].
-; This number is divided by 4. The result is 8 bit (reg. a).
-; Always bigger than zero.
+; Divide the enemy's current HP by 4. HP is not supposed to exceed 999 so
+; the result should fit in a. If the division results in a quotient of 0,
+; change it to 1.
+	ld hl,wEnemyMonHP
+	ld a,[hli]
+	ld b,a
+	ld a,[hl]
 	srl b
 	rr a
 	srl b
-	rr a ; a = current HP / 4
+	rr a
 	and a
-	jr nz, .next8
+	jr nz,.skip2
 	inc a
-.next8
-	ld [H_DIVISOR], a
-	ld b, 4
-	call Divide	; ((MaxHP * 255) / BallFactor) / (CurHP / 4)
-	ld a, [H_QUOTIENT + 2]
+
+.skip2
+
+; Let W = ((MaxHP * 255) / BallFactor) / max(HP / 4, 1). Calculate W.
+	ld [H_DIVISOR],a
+	ld b,4
+	call Divide
+
+; If W > 255, store 255 in [H_QUOTIENT + 3].
+; Let X = min(W, 255) = [H_QUOTIENT + 3].
+	ld a,[H_QUOTIENT + 2]
 	and a
-	jr z, .next9
-	ld a, 255
-	ld [H_QUOTIENT + 3], a
-.next9
-	pop bc
-	ld a, [wEnemyMonCatchRate]	;enemy: Catch Rate
+	jr z,.skip3
+	ld a,255
+	ld [H_QUOTIENT + 3],a
+
+.skip3
+	pop bc ; b = Rand1 - Status
+
+; If Rand1 - Status > CatchRate, the ball fails to capture the Pokémon.
+	ld a,[wEnemyMonCatchRate]
 	cp b
-	jr c, .next10
-	ld a, [H_QUOTIENT + 2]
+	jr c,.failedToCapture
+
+; If W > 255, the ball captures the Pokémon.
+	ld a,[H_QUOTIENT + 2]
 	and a
-	jr nz, .BallSuccess ; if ((MaxHP * 255) / BallFactor) / (CurHP / 4) > 0x255, automatic success
-	call Random
-	ld b, a
-	ld a, [H_QUOTIENT + 3]
+	jr nz,.captured
+
+	call Random ; Let this random number be called Rand2.
+
+; If Rand2 > X, the ball fails to capture the Pokémon.
+	ld b,a
+	ld a,[H_QUOTIENT + 3]
 	cp b
-	jr c, .next10
-.BallSuccess
-	jr .BallSuccess2
+	jr c,.failedToCapture
 
-.next10
-	ld a, [H_QUOTIENT + 3]
-	ld [wd11e], a
+.captured
+	jr .skipShakeCalculations
+
+.failedToCapture
+	ld a,[H_QUOTIENT + 3]
+	ld [wPokeBallCaptureCalcTemp],a ; Save X.
+
+; Calculate CatchRate * 100.
 	xor a
-	ld [H_MULTIPLICAND], a
-	ld [H_MULTIPLICAND + 1], a
-	ld a, [wEnemyMonCatchRate]	;enemy: Catch Rate
-	ld [H_MULTIPLICAND + 2], a
-	ld a, 100
-	ld [H_MULTIPLIER], a
-	call Multiply	; CatchRate * 100
-	ld a, [wcf91]
-	ld b, 255
+	ld [H_MULTIPLICAND],a
+	ld [H_MULTIPLICAND + 1],a
+	ld a,[wEnemyMonCatchRate]
+	ld [H_MULTIPLICAND + 2],a
+	ld a,100
+	ld [H_MULTIPLIER],a
+	call Multiply
+
+; Determine BallFactor2.
+; Poké Ball:         BallFactor2 = 255
+; Great Ball:        BallFactor2 = 200
+; Ultra/Safari Ball: BallFactor2 = 150
+	ld a,[wcf91]
+	ld b,255
 	cp POKE_BALL
-	jr z, .next11
-	ld b, 200
+	jr z,.skip4
+	ld b,200
 	cp GREAT_BALL
-	jr z, .next11
-	ld b, 150
+	jr z,.skip4
+	ld b,150
 	cp ULTRA_BALL
-	jr z, .next11
-.next11
-	ld a, b
-	ld [H_DIVISOR], a
-	ld b, 4
+	jr z,.skip4
+
+.skip4
+
+; Let Y = (CatchRate * 100) / BallFactor2. Calculate Y.
+	ld a,b
+	ld [H_DIVISOR],a
+	ld b,4
 	call Divide
-	ld a, [H_QUOTIENT + 2]
+
+; If Y > 255, there are 3 shakes.
+; Note that this shouldn't be possible.
+; The maximum value of Y is (255 * 100) / 150 = 170.
+	ld a,[H_QUOTIENT + 2]
 	and a
-	ld b, $63
-	jr nz, .next12
-	ld a, [wd11e]
-	ld [H_MULTIPLIER], a
+	ld b,$63 ; 3 shakes
+	jr nz,.setAnimData
+
+; Calculate X * Y.
+	ld a,[wPokeBallCaptureCalcTemp]
+	ld [H_MULTIPLIER],a
 	call Multiply
-	ld a, 255
-	ld [H_DIVISOR], a
-	ld b, 4
+
+; Calculate (X * Y) / 255.
+	ld a,255
+	ld [H_DIVISOR],a
+	ld b,4
 	call Divide
-	ld a, [wEnemyMonStatus]	;status ailments
+	
+; Determine Status2.
+; no status ailment:     Status2 = 0
+; Burn/Paralysis/Poison: Status2 = 5
+; Freeze/Sleep:          Status2 = 10
+	ld a,[wEnemyMonStatus]
 	and a
-	jr z, .next13
+	jr z,.skip5
 	and 1 << FRZ | SLP
-	ld b, 5
-	jr z, .next14
-	ld b, 10
-.next14
-	ld a, [H_QUOTIENT + 3]
+	ld b,5
+	jr z,.addAilmentValue
+	ld b,10
+
+.addAilmentValue
+; If the Pokémon has a status ailment, add Status2.
+	ld a,[H_QUOTIENT + 3]
 	add b
-	ld [H_QUOTIENT + 3], a
-.next13
-	ld a, [H_QUOTIENT + 3]
-	cp 10
-	ld b, $20
-	jr c, .next12
-	cp 30
-	ld b, $61
-	jr c, .next12
-	cp 70
-	ld b, $62
-	jr c, .next12
-	ld b, $63
-.next12
-	ld a, b
-	ld [wPokeBallAnimData], a
-.BallSuccess2
-	ld c, 20
+	ld [H_QUOTIENT + 3],a
+
+.skip5
+; Finally determine the number of shakes.
+; Let Z = ((X * Y) / 255) + Status2 = [H_QUOTIENT + 3].
+; The number of shakes depend on the range Z is in.
+; 0  ≤ Z < 10: 0 shakes (the ball misses)
+; 10 ≤ Z < 30: 1 shake
+; 30 ≤ Z < 70: 2 shakes
+; 70 ≤ Z:      3 shakes
+	ld a,[H_QUOTIENT + 3]
+	cp a,10
+	ld b,$20
+	jr c,.setAnimData
+	cp a,30
+	ld b,$61
+	jr c,.setAnimData
+	cp a,70
+	ld b,$62
+	jr c,.setAnimData
+	ld b,$63
+
+.setAnimData
+	ld a,b
+	ld [wPokeBallAnimData],a
+
+.skipShakeCalculations
+	ld c,20
 	call DelayFrames
-	ld a, TOSS_ANIM
-	ld [wAnimationID], a
+
+; Do the animation.
+	ld a,TOSS_ANIM
+	ld [wAnimationID],a
 	xor a
 	ld [H_WHOSETURN], a
 	ld [wAnimationType], a
@@ -347,48 +448,63 @@ ItemUseBall: ; d3ad (3:53ad)
 	pop af
 	ld [wcf91], a
 	pop af
-	ld [wWhichPokemon], a
-	ld a, [wPokeBallAnimData]
-	cp $10
-	ld hl, ItemUseBallText00
-	jp z, .printText0
-	cp $20
-	ld hl, ItemUseBallText01
-	jp z, .printText0
-	cp $61
-	ld hl, ItemUseBallText02
-	jp z, .printText0
-	cp $62
-	ld hl, ItemUseBallText03
-	jp z, .printText0
-	cp $63
-	ld hl, ItemUseBallText04
-	jp z, .printText0
-	ld hl, wEnemyMonHP	;current HP
-	ld a, [hli]
+	ld [wWhichPokemon],a
+
+; Determine the message to display from the animation.
+	ld a,[wPokeBallAnimData]
+	cp a,$10
+	ld hl,ItemUseBallText00
+	jp z,.printMessage
+	cp a,$20
+	ld hl,ItemUseBallText01
+	jp z,.printMessage
+	cp a,$61
+	ld hl,ItemUseBallText02
+	jp z,.printMessage
+	cp a,$62
+	ld hl,ItemUseBallText03
+	jp z,.printMessage
+	cp a,$63
+	ld hl,ItemUseBallText04
+	jp z,.printMessage
+
+; Save current HP.
+	ld hl,wEnemyMonHP
+	ld a,[hli]
 	push af
-	ld a, [hli]
-	push af		;backup currentHP...
+	ld a,[hli]
+	push af
+
+; Save status ailment.
 	inc hl
-	ld a, [hl]
-	push af		;...and status ailments
+	ld a,[hl]
+	push af
+
 	push hl
-	ld hl, wEnemyBattleStatus3
-	bit Transformed, [hl]
-	jr z, .next15
-	ld a, $4c
-	ld [wEnemyMonSpecies2], a
-	jr .next16
-
-.next15
-	set Transformed, [hl]
-	ld hl, wTransformedEnemyMonOriginalDVs
-	ld a, [wEnemyMonDVs]
-	ld [hli], a
-	ld a, [wEnemyMonDVs + 1]
-	ld [hl], a
-.next16
-	ld a, [wcf91]
+
+; If the Pokémon is transformed, the Pokémon is assumed to be a Ditto.
+; This is a bug because a wild Pokémon could have used Transform via
+; Mirror Move even though the only wild Pokémon that knows Transform is Ditto.
+	ld hl,wEnemyBattleStatus3
+	bit Transformed,[hl]
+	jr z,.notTransformed
+	ld a,DITTO
+	ld [wEnemyMonSpecies2],a
+	jr .skip6
+
+.notTransformed
+; If the Pokémon is not transformed, set the transformed bit and copy the
+; DVs to wTransformedEnemyMonOriginalDVs so that LoadEnemyMonData won't generate
+; new DVs.
+	set Transformed,[hl]
+	ld hl,wTransformedEnemyMonOriginalDVs
+	ld a,[wEnemyMonDVs]
+	ld [hli],a
+	ld a,[wEnemyMonDVs + 1]
+	ld [hl],a
+
+.skip6
+	ld a,[wcf91]
 	push af
 	ld a, [wEnemyMonSpecies2]
 	ld [wcf91], a
@@ -404,18 +520,20 @@ ItemUseBall: ; d3ad (3:53ad)
 	pop af
 	ld [hld], a
 	pop af
-	ld [hl], a
-	ld a, [wEnemyMonSpecies]	;enemy
-	ld [wCapturedMonSpecies], a
-	ld [wcf91], a
-	ld [wd11e], a
-	ld a, [wBattleType]
-	cp $1
-	jp z, .printText1 ; just barely out of reach for a relative jump
-	cp $4
-	jr z, .printText1
-	ld hl, ItemUseBallText05
+	ld [hl],a
+	ld a,[wEnemyMonSpecies]
+	ld [wCapturedMonSpecies],a
+	ld [wcf91],a
+	ld [wd11e],a
+	ld a,[wBattleType]
+	cp BATTLE_TYPE_OLD_MAN ; is this the old man battle?
+	jp z,.oldManCaughtMon ; if so, don't give the player the caught Pokémon
+	cp BATTLE_TYPE_PIKACHU
+	jr z,.oldManCaughtMon ; same with Pikachu battle
+	ld hl,ItemUseBallText05
 	call PrintText
+
+; Add the caught Pokémon to the Pokédex.
 	predef IndexToPokedex
 	ld a, [wd11e]
 	dec a
@@ -431,51 +549,58 @@ ItemUseBall: ; d3ad (3:53ad)
 	ld b, FLAG_SET
 	predef FlagActionPredef
 	pop af
-	and a
-	jr nz, .checkParty
-	ld hl, ItemUseBallText06
+
+	and a ; was the Pokémon already in the Pokédex?
+	jr nz,.skipShowingPokedexData ; if so, don't show the Pokédex data
+
+	ld hl,ItemUseBallText06
 	call PrintText
 	call ClearSprites
-	ld a, [wEnemyMonSpecies]	;caught mon_ID
-	ld [wd11e], a
+	ld a,[wEnemyMonSpecies]
+	ld [wd11e],a
 	predef ShowPokedexData
-.checkParty
+
+.skipShowingPokedexData
 	ld a, $1
 	ld [wd49c], a
 	ld a, $85
 	ld [wPikachuMood], a
-	ld a, [wPartyCount]
-	cp PARTY_LENGTH		;is party full?
-	jr z, .sendToBox
+	ld a,[wPartyCount]
+	cp PARTY_LENGTH ; is party full?
+	jr z,.sendToBox
 	xor a ; PLAYER_PARTY_DATA
 	ld [wMonDataLocation], a
 	call ClearSprites
 	ld hl, .emptyString
 	call PrintText
-	call AddPartyMon	;add mon to Party
-	jr .End
+	call AddPartyMon
+	jr .done
 
 .sendToBox
 	call ClearSprites
 	call SendNewMonToBox
-	ld hl, ItemUseBallText07
+	ld hl,ItemUseBallText07
 	CheckEvent EVENT_MET_BILL
-	jr nz, .sendToBox2
-	ld hl, ItemUseBallText08
-.sendToBox2
+	jr nz,.printTransferredToPCText
+	ld hl,ItemUseBallText08
+.printTransferredToPCText
 	call PrintText
-	jr .End
+	jr .done
+
+.oldManCaughtMon
+	ld hl,ItemUseBallText05
 
-.printText1
-	ld hl, ItemUseBallText05
-.printText0
+.printMessage
 	call PrintText
 	call ClearSprites
-.End
-	ld a, [wBattleType]
-	and a
-	ret nz
-	ld hl, wNumBagItems
+
+.done
+	ld a,[wBattleType]
+	and a ; is this the old man battle?
+	ret nz ; if so, don't remove a ball from the bag
+
+; Remove a ball from the bag.
+	ld hl,wNumBagItems
 	inc a
 	ld [wItemQuantity], a
 	jp RemoveItemFromInventory
@@ -839,9 +964,9 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	jr nc, .healHP ; if it's a Full Restore or one of the potions
 ; fall through if it's one of the status-specifc healing items
 .cureStatusAilment
-	ld bc, 4
-	add hl, bc ; hl now points to status
-	ld a, [wcf91]
+	ld bc,wPartyMon1Status - wPartyMon1
+	add hl,bc ; hl now points to status
+	ld a,[wcf91]
 	lb bc, ANTIDOTE_MSG, 1 << PSN
 	cp ANTIDOTE
 	jr z, .checkMonStatus
@@ -877,10 +1002,10 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	ld hl, wPlayerBattleStatus3
 	res BadlyPoisoned, [hl] ; heal Toxic status
 	pop hl
-	ld bc, 30
-	add hl, bc ; hl now points to party stats
-	ld de, wBattleMonMaxHP
-	ld bc, 10
+	ld bc,wPartyMon1Stats - wPartyMon1Status
+	add hl,bc ; hl now points to party stats
+	ld de,wBattleMonStats
+	ld bc,NUM_STATS * 2
 	call CopyData ; copy party stats to in-battle stat data
 	predef DoubleOrHalveSelectedStats
 	jp .doneHealing
@@ -952,8 +1077,8 @@ ItemUseMedicine: ; d8ae (3:58ae)
 .compareCurrentHPToMaxHP
 	push hl
 	push bc
-	ld bc, 32
-	add hl, bc ; hl now points to max HP
+	ld bc,wPartyMon1MaxHP - (wPartyMon1HP + 1)
+	add hl,bc ; hl now points to max HP
 	pop bc
 	ld a, [hli]
 	cp b
@@ -985,13 +1110,13 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	ld [wChannelSoundIDs + CH4], a
 	push hl
 	push de
-	ld bc, 32
-	add hl, bc ; hl now points to max HP
-	ld a, [hli]
-	ld [wHPBarMaxHP+1], a
-	ld a, [hl]
-	ld [wHPBarMaxHP], a ; max HP stored at wHPBarMaxHP (2 bytes, big-endian)
-	ld a, [wPseudoItemID]
+	ld bc,wPartyMon1MaxHP - (wPartyMon1HP + 1)
+	add hl,bc ; hl now points to max HP
+	ld a,[hli]
+	ld [wHPBarMaxHP+1],a
+	ld a,[hl]
+	ld [wHPBarMaxHP],a ; max HP stored at wHPBarMaxHP (2 bytes, big-endian)
+	ld a,[wPseudoItemID]
 	and a ; using Softboiled?
 	jp z, .notUsingSoftboiled2
 ; if using softboiled
@@ -1018,8 +1143,8 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	ld [H_DIVISOR], a
 	ld b, 2 ; number of bytes
 	call Divide ; get 1/5 of max HP of pokemon that used Softboiled
-	ld bc, wPartyMon1HP - wPartyMon1MaxHP
-	add hl, bc ; hl now points to LSB of current HP of pokemon that used Softboiled
+	ld bc,(wPartyMon1HP + 1) - (wPartyMon1MaxHP + 1)
+	add hl,bc ; hl now points to LSB of current HP of pokemon that used Softboiled
 ; subtract 1/5 of max HP from current HP of pokemon that used Softboiled
 	ld a, [H_QUOTIENT + 3]
 	push af
@@ -1096,16 +1221,16 @@ ItemUseMedicine: ; d8ae (3:58ae)
 .noCarry
 	push de
 	inc hl
-	ld d, h
-	ld e, l ; de now points to current HP
-	ld hl, 33
-	add hl, de ; hl now points to max HP
-	ld a, [wcf91]
-	cp REVIVE
-	jr z, .setCurrentHPToHalfMaxHP
-	ld a, [hld]
-	ld b, a
-	ld a, [de]
+	ld d,h
+	ld e,l ; de now points to current HP
+	ld hl,(wPartyMon1MaxHP + 1) - (wPartyMon1HP + 1)
+	add hl,de ; hl now points to max HP
+	ld a,[wcf91]
+	cp a,REVIVE
+	jr z,.setCurrentHPToHalfMaxHP
+	ld a,[hld]
+	ld b,a
+	ld a,[de]
 	sub b
 	dec de
 	ld b, [hl]
@@ -1144,11 +1269,11 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	ld [wHPBarNewHP], a
 	dec de
 .doneHealingPartyHP ; done updating the pokemon's current HP in the party data structure
-	ld a, [wcf91]
-	cp FULL_RESTORE
-	jr nz, .updateInBattleData
-	ld bc, -31
-	add hl, bc
+	ld a,[wcf91]
+	cp a,FULL_RESTORE
+	jr nz,.updateInBattleData
+	ld bc,wPartyMon1Status - (wPartyMon1MaxHP + 1)
+	add hl,bc
 	xor a
 	ld [hl], a ; remove the status ailment in the party data
 .updateInBattleData
@@ -1169,8 +1294,8 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	xor a
 	ld [wBattleMonStatus], a ; remove the status ailment in the in-battle pokemon data
 .calculateHPBarCoords
-	ld hl, wOAMBuffer + $90
-	ld bc, 2 * 20
+	ld hl,wOAMBuffer + $90
+	ld bc,2 * SCREEN_WIDTH
 	inc d
 .calculateHPBarCoordsLoop
 	add hl, bc
@@ -1252,13 +1377,13 @@ ItemUseMedicine: ; d8ae (3:58ae)
 
 .useVitamin
 	push hl
-	ld a, [hl]
-	ld [wd0b5], a
-	ld [wd11e], a
-	ld bc, 33
-	add hl, bc ; hl now points to level
-	ld a, [hl] ; a = level
-	ld [wCurEnemyLVL], a ; store level
+	ld a,[hl]
+	ld [wd0b5],a
+	ld [wd11e],a
+	ld bc,wPartyMon1Level - wPartyMon1
+	add hl,bc ; hl now points to level
+	ld a,[hl] ; a = level
+	ld [wCurEnemyLVL],a ; store level
 	call GetMonHeader
 	push de
 	ld a, d
@@ -1272,8 +1397,8 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	push hl
 	sub HP_UP
 	add a
-	ld bc, 17
-	add hl, bc
+	ld bc,wPartyMon1HPExp - wPartyMon1
+	add hl,bc
 	add l
 	ld l, a
 	jr nc, .noCarry2
@@ -1323,21 +1448,21 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	jp GBPalWhiteOut
 
 .recalculateStats
-	ld bc, 34
-	add hl, bc
-	ld d, h
-	ld e, l ; de now points to stats
-	ld bc, -18
-	add hl, bc ; hl now points to byte 3 of experience
-	ld b, 1
+	ld bc,wPartyMon1Stats - wPartyMon1
+	add hl,bc
+	ld d,h
+	ld e,l ; de now points to stats
+	ld bc,(wPartyMon1Exp + 2) - wPartyMon1Stats
+	add hl,bc ; hl now points to LSB of experience
+	ld b,1
 	jp CalcStats ; recalculate stats
 .useRareCandy
 	push hl
-	ld bc, 33
-	add hl, bc ; hl now points to level
-	ld a, [hl] ; a = level
-	cp MAX_LEVEL
-	jr z, .vitaminNoEffect ; can't raise level above 100
+	ld bc,wPartyMon1Level - wPartyMon1
+	add hl,bc ; hl now points to level
+	ld a,[hl] ; a = level
+	cp a, MAX_LEVEL
+	jr z,.vitaminNoEffect ; can't raise level above 100
 	inc a
 	ld [hl], a ; store incremented level
 	ld [wCurEnemyLVL], a
@@ -1347,8 +1472,8 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	callab CalcExperience ; calculate experience for next level and store it at $ff96
 	pop de
 	pop hl
-	ld bc, -19
-	add hl, bc ; hl now points to experience
+	ld bc,wPartyMon1Exp - wPartyMon1Level
+	add hl,bc ; hl now points to MSB of experience
 ; update experience to minimum for new level
 	ld a, [hExperience]
 	ld [hli], a
@@ -1363,18 +1488,18 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	push af
 	push de
 	push hl
-	ld bc, 34
-	add hl, bc ; hl now points to MSB of max HP
-	ld a, [hli]
-	ld b, a
-	ld c, [hl]
+	ld bc,wPartyMon1MaxHP - wPartyMon1
+	add hl,bc ; hl now points to MSB of max HP
+	ld a,[hli]
+	ld b,a
+	ld c,[hl]
 	pop hl
 	push bc
 	push hl
 	call .recalculateStats
 	pop hl
-	ld bc, 35 ; hl now points to LSB of max HP
-	add hl, bc
+	ld bc,(wPartyMon1MaxHP + 1) - wPartyMon1
+	add hl,bc ; hl now points to LSB of max HP
 	pop bc
 	ld a, [hld]
 	sub c
@@ -1383,9 +1508,9 @@ ItemUseMedicine: ; d8ae (3:58ae)
 	sbc b
 	ld b, a ; bc = the amount of max HP gained from leveling up
 ; add the amount gained to the current HP
-	ld de, -32
-	add hl, de ; hl now points to MSB of current HP
-	ld a, [hl]
+	ld de,(wPartyMon1HP + 1) - wPartyMon1MaxHP
+	add hl,de ; hl now points to LSB of current HP
+	ld a,[hl]
 	add c
 	ld [hld], a
 	ld a, [hl]
@@ -1575,10 +1700,10 @@ ItemUseCardKey: ; de57 (3:de57)
 	xor a
 	ld [wUnusedD71F], a
 	call GetTileAndCoordsInFrontOfPlayer
-	ld a, [GetTileAndCoordsInFrontOfPlayer] ; $4586
-	cp $18
-	jr nz, .next0
-	ld hl, CardKeyTable1
+	ld a,[GetTileAndCoordsInFrontOfPlayer]
+	cp a,$18
+	jr nz,.next0
+	ld hl,CardKeyTable1
 	jr .next1
 
 .next0
@@ -2153,12 +2278,12 @@ ItemUsePPRestore: ; e1f7 (3:61f7)
 	cp ETHER
 	jr nc, .useEther ; if Ether or Max Ether
 .usePPUp
-	ld bc, 21
-	add hl, bc
-	ld a, [hl] ; move PP
-	cp 3 << 6 ; have 3 PP Ups already been used?
-	jr c, .PPNotMaxedOut
-	ld hl, PPMaxedOutText
+	ld bc,wPartyMon1PP - wPartyMon1Moves
+	add hl,bc
+	ld a,[hl] ; move PP
+	cp a,3 << 6 ; have 3 PP Ups already been used?
+	jr c,.PPNotMaxedOut
+	ld hl,PPMaxedOutText
 	call PrintText
 	jr .chooseMove
 
diff --git a/engine/menu/link_menu.asm b/engine/menu/link_menu.asm
index becefd47..4d0beb7e 100644
--- a/engine/menu/link_menu.asm
+++ b/engine/menu/link_menu.asm
@@ -776,7 +776,7 @@ LinkMenu: ; f580c (3d:580c)
 	call DelayFrames
 	ld hl, wd732
 	res 1, [hl]
-	ld a, [wAnimationID]
+	ld a, [wDefaultMap]
 	ld [wDestinationMap], a
 	callab SpecialWarpIn
 	ld c, 20
diff --git a/engine/menu/main_menu.asm b/engine/menu/main_menu.asm
index fb3fb6b9..669b2ba8 100755
--- a/engine/menu/main_menu.asm
+++ b/engine/menu/main_menu.asm
@@ -20,7 +20,7 @@ MainMenu: ; 5ba6 (1:5ba6)
 	ld [hli],a
 	ld [hli],a
 	ld [hl],a
-	ld [wAnimationID],a
+	ld [wDefaultMap],a
 	ld hl,wd72e
 	res 6,[hl]
 	call ClearScreen
@@ -88,7 +88,7 @@ MainMenu: ; 5ba6 (1:5ba6)
 	jp .mainMenuLoop
 .choseContinue
 	call DisplayContinueGameInfo
-	ld hl,wd126
+	ld hl,wCurrentMapScriptFlags
 	set 5,[hl]
 .inputLoop
 	xor a
@@ -247,12 +247,12 @@ PrintNumOwnedMons: ; 5daa (1:5daa)
 	jp PrintNumber
 
 PrintPlayTime: ; 5dbd (1:5dbd)
-	ld de, wPlayTimeHours + 1
+	ld de, wPlayTimeHours
 	lb bc, 1, 3
 	call PrintNumber
 	ld [hl], $6d
 	inc hl
-	ld de, wPlayTimeMinutes + 1
+	ld de, wPlayTimeMinutes
 	lb bc, LEADING_ZEROES | 1, 2
 	jp PrintNumber
 
diff --git a/engine/menu/naming_screen.asm b/engine/menu/naming_screen.asm
index de0c696c..0eacc8f6 100755
--- a/engine/menu/naming_screen.asm
+++ b/engine/menu/naming_screen.asm
@@ -164,7 +164,7 @@ DisplayNamingScreen: ; 6307 (1:6307)
 	call RunDefaultPaletteCommand
 	call GBPalNormal
 	xor a
-	ld [wSubAnimTransform], a
+	ld [wAnimCounter], a
 	ld hl, wd730
 	res 6, [hl]
 	ld a, [wIsInBattle]
diff --git a/engine/menu/start_sub_menus.asm b/engine/menu/start_sub_menus.asm
index e2491253..792903b7 100755
--- a/engine/menu/start_sub_menus.asm
+++ b/engine/menu/start_sub_menus.asm
@@ -163,7 +163,7 @@ StartMenu_Pokemon: ; 11c36 (4:5c36)
 .surf ; 11d66 (4:5d66)
 	bit 4,a ; does the player have the Soul Badge?
 	jp z,.newBadgeRequired
-	callba CheckForForcedBikeSurf
+	callba IsSurfingAllowed
 	ld hl,wd728
 	bit 1,[hl]
 	res 1,[hl]
@@ -618,12 +618,12 @@ DrawTrainerInfo: ; 1204c (4:604c)
 	ld c,$e3
 	call PrintBCDNumber
 	coord hl, 9, 6
-	ld de,wPlayTimeHours + 1 ; hours
+	ld de,wPlayTimeHours ; hours
 	lb bc, LEFT_ALIGN | 1, 3
 	call PrintNumber
 	ld [hl],$d6 ; colon tile ID
 	inc hl
-	ld de,wPlayTimeMinutes + 1 ; minutes
+	ld de,wPlayTimeMinutes ; minutes
 	lb bc, LEADING_ZEROES | 1, 2
 	jp PrintNumber
 
diff --git a/engine/oak_speech.asm b/engine/oak_speech.asm
index 925ff913..2726c651 100755
--- a/engine/oak_speech.asm
+++ b/engine/oak_speech.asm
@@ -56,7 +56,7 @@ OakSpeech: ; 5e85 (1:5e85)
 	ld a,1
 	ld [wItemQuantity],a
 	call AddItemToInventory  ; give one potion
-	ld a,[wAnimationID]
+	ld a,[wDefaultMap]
 	ld [wDestinationMap],a
 	call SpecialWarpIn
 	xor a
@@ -225,8 +225,8 @@ IntroDisplayPicCenteredOrUpperRight: ; 6010 (1:6010)
 	call UncompressSpriteFromDE
 	ld a, $0
 	call SwitchSRAMBankAndLatchClockData
-	ld hl,S_SPRITEBUFFER1
-	ld de,S_SPRITEBUFFER0
+	ld hl,sSpriteBuffer1
+	ld de,sSpriteBuffer0
 	ld bc,$310
 	call CopyData
 	call PrepareRTCDataAndDisableSRAM
diff --git a/engine/oak_speech2.asm b/engine/oak_speech2.asm
index 37c998a9..5eeb5ea9 100755
--- a/engine/oak_speech2.asm
+++ b/engine/oak_speech2.asm
@@ -226,9 +226,16 @@ GetDefaultName: ; 6858 (1:6858)
 	jp CopyData
 
 DefaultNamesPlayerList: ; 687d (1:687d)
-	db "NEW NAME@YELLOW@ASH@JACK@"
+	db "NEW NAME@"
+	db "YELLOW@"
+	db "ASH@"
+	db "JACK@"
+
 DefaultNamesRivalList: ; 688d (1:688d)
-	db "NEW NAME@BLUE@GARY@JOHN@"
+	db "NEW NAME@"
+	db "BLUE@"
+	db "GARY@"
+	db "JOHN@"
 
 TextTerminator_6b20: ; 68a5 (1:68a5)
 	db "@"
diff --git a/engine/overworld/card_key.asm b/engine/overworld/card_key.asm
index 62d1d4fb..3560c8e8 100755
--- a/engine/overworld/card_key.asm
+++ b/engine/overworld/card_key.asm
@@ -50,7 +50,7 @@ PrintCardKeyText: ; 525d8 (14:65d8)
 .replaceCardKeyDoorTileBlock
 	ld [wNewTileBlockID], a
 	predef ReplaceTileBlock
-	ld hl, wd126
+	ld hl, wCurrentMapScriptFlags
 	set 5, [hl]
 	ld a, SFX_GO_INSIDE
 	jp PlaySound
diff --git a/engine/overworld/cinnabar_lab.asm b/engine/overworld/cinnabar_lab.asm
index f81324e0..f7c5e326 100755
--- a/engine/overworld/cinnabar_lab.asm
+++ b/engine/overworld/cinnabar_lab.asm
@@ -48,9 +48,9 @@ GiveFossilToCinnabarLab: ; 61006 (18:5006)
 .choseDomeFossil
 	ld b, KABUTO
 .fossilSelected
-	ld [W_FOSSILITEM], a
+	ld [wFossilItem], a
 	ld a, b
-	ld [W_FOSSILMON], a
+	ld [wFossilMon], a
 	call LoadFossilItemAndMonName
 	ld hl, LabFossil_610ae
 	call PrintText
@@ -60,7 +60,7 @@ GiveFossilToCinnabarLab: ; 61006 (18:5006)
 	jr nz, .cancelledGivingFossil
 	ld hl, LabFossil_610b3
 	call PrintText
-	ld a, [W_FOSSILITEM]
+	ld a, [wFossilItem]
 	ld [hItemToRemoveID], a
 	callba RemoveItemByID
 	ld hl, LabFossil_610b8
@@ -113,11 +113,11 @@ PrintFossilsInBag: ; 610c2 (18:50c2)
 
 ; loads the names of the fossil item and the resulting mon
 LoadFossilItemAndMonName: ; 610eb (18:50eb)
-	ld a, [W_FOSSILMON]
+	ld a, [wFossilMon]
 	ld [wd11e], a
 	call GetMonName
 	call CopyStringToCF4B
-	ld a, [W_FOSSILITEM]
+	ld a, [wFossilItem]
 	ld [wd11e], a
 	call GetItemName
 	ret
diff --git a/engine/overworld/movement.asm b/engine/overworld/movement.asm
index 5f929ce3..d69e2fbc 100644
--- a/engine/overworld/movement.asm
+++ b/engine/overworld/movement.asm
@@ -118,8 +118,8 @@ UpdateNPCSprite: ; 4e3e (1:4e3e)
 	ld l, a
 	inc l
 	ld a, [hl]        ; c1x1
-	bit 7, a
-	jp nz, InitializeSpriteFacingDirection  ; c1x1 >= $80
+	bit 7, a ; is the face player flag set?
+	jp nz, MakeNPCFacePlayer
 	ld b, a
 	ld a, [wFontLoaded]
 	bit 0, a
@@ -156,7 +156,7 @@ UpdateNPCSprite: ; 4e3e (1:4e3e)
 	call LoadDEPlusA ; a = [wNPCMovementDirections + movement byte 1]
 	cp $e0
 	jp z, ChangeFacingDirection
-	cp $ff
+	cp STAY
 	jr nz, .next
 ; reached end of wNPCMovementDirections list
 	ld [hl], a ; store $ff in movement byte 1, disabling scripted movement
@@ -167,7 +167,7 @@ UpdateNPCSprite: ; 4e3e (1:4e3e)
 	ld [wWastedByteCD3A], a
 	ret
 .next
-	cp $fe
+	cp WALK
 	jr nz, .asm_4ecb
 ; current NPC movement data is $fe. this seems buggy
 	ld [hl], $1     ; set movement byte 1 to $1
@@ -359,7 +359,11 @@ notYetMoving: ; 4fc5 (1:4fc5)
 	ld [hl], $0             ; c1x8 = 0 (walk animation frame)
 	jp UpdateSpriteImage
 
-InitializeSpriteFacingDirection: ; 4fd1 (1:4fd1)
+MakeNPCFacePlayer: ; 507f (1:507f)
+; Make an NPC face the player if the player has spoken to him or her.
+
+; Check if the behaviour of the NPC facing the player when spoken to is
+; disabled. This is only done when rubbing the S.S. Anne captain's back.
 	ld a, [wd72d]
 	bit 5, a
 	jr nz, notYetMoving
diff --git a/engine/overworld/special_warps.asm b/engine/overworld/special_warps.asm
index 29000d98..8c1b4159 100644
--- a/engine/overworld/special_warps.asm
+++ b/engine/overworld/special_warps.asm
@@ -69,7 +69,7 @@ LoadSpecialWarpData: ; 6073 (1:6073)
 	xor a
 	jr .done
 .notFirstMap
-	ld a, [wLastMap]
+	ld a, [wLastMap] ; this value is overwritten before it's ever read
 	ld hl, wd732
 	bit 4, [hl] ; used dungeon warp (jumped down hole/waterfall)?
 	jr nz, .usedDunegonWarp
diff --git a/engine/pikachu_pic_animation.asm b/engine/pikachu_pic_animation.asm
index 1d91150e..be31e7d7 100755
--- a/engine/pikachu_pic_animation.asm
+++ b/engine/pikachu_pic_animation.asm
@@ -664,10 +664,10 @@ DecompressRequestPikaPicAnimGFX: ; fe128
 	jr c, .failed
 	ld a, b
 	call UncompressSpriteFromDE
-	ld a, BANK(S_SPRITEBUFFER1)
+	ld a, BANK(sSpriteBuffer1)
 	call SwitchSRAMBankAndLatchClockData
-	ld hl, S_SPRITEBUFFER1
-	ld de, S_SPRITEBUFFER0
+	ld hl, sSpriteBuffer1
+	ld de, sSpriteBuffer0
 	ld bc, SPRITEBUFFERSIZE * 2
 	call CopyData
 	call PrepareRTCDataAndDisableSRAM
diff --git a/engine/predefs7.asm b/engine/predefs7.asm
index 9138897f..1bf4c018 100755
--- a/engine/predefs7.asm
+++ b/engine/predefs7.asm
@@ -25,7 +25,7 @@ DisplayElevatorFloorMenu: ; 1c264 (7:4264)
 	ld a, b
 	ld [wListScrollOffset], a
 	ret c
-	ld hl, wd126
+	ld hl, wCurrentMapScriptFlags
 	set 7, [hl]
 	ld hl, wElevatorWarpMaps
 	ld a, [wWhichPokemon]
diff --git a/engine/titlescreen.asm b/engine/titlescreen.asm
index 74374dcf..8da93f17 100755
--- a/engine/titlescreen.asm
+++ b/engine/titlescreen.asm
@@ -362,7 +362,7 @@ IncrementResetCounter: ; 4405 (1:4405)
 FillSpriteBuffer0WithAA: ; 4418 (1:4418)
 	xor a
 	call SwitchSRAMBankAndLatchClockData
-	ld hl, S_SPRITEBUFFER0
+	ld hl, sSpriteBuffer0
 	ld bc, $20
 	ld a, $aa
 	call FillMemory
diff --git a/engine/town_map.asm b/engine/town_map.asm
index 82e24d75..47812db0 100755
--- a/engine/town_map.asm
+++ b/engine/town_map.asm
@@ -454,8 +454,12 @@ WritePlayerOrBirdSpriteOAM: ; 712f6 (1c:52f6)
 
 WriteTownMapSpriteOAM: ; 71302 (1c:5302)
 	push hl
+
+; Subtract 4 from c (X coord) and 4 from b (Y coord). However, the carry from c
+; is added to b, so the net result is that only 3 is subtracted from b.
 	lb hl, -4, -4
-	add hl, bc ; subtract 4 from c (X coord) and 4 from b (Y coord)
+	add hl, bc
+
 	ld b, h
 	ld c, l
 	pop hl