Port PureRGB AI

Short tests showed positive results. Revert if it fucks up anything.

PureRGB enhances Gen 1 AI in various ways, fixing notorious glitches and making it not do completely stupid things. I would use shin pokered's, but it may be too difficult for unfamiliar players, and has a bunch of outdated markers I'd have to spruce up.

Relevant changes:
- Burn effect calls have been replaced with Fire Blast's effect, replicating the burn spread use-case of Fire Blast
- Teleport references removed because pureRGB uses a unique version
- Any straggler references to effects not used in pureRGB
- Mist properly referred to as we only have one move that provides stat drop immunity.

Updated the sprite gallery too!!

engine/battle/unused_stats_functions.asm

@@ -1,4 +1,37 @@
-; does nothing since no stats are ever selected (barring glitches)
+; Used by the pureRGB AI
+;shinpokerednote: ADDED: doubles attack if burned or quadruples speed if paralyzed.
+;It's meant to be run right before healing paralysis or burn so as to 
+;undo the stat changes.
+UndoBurnParStats:
+	ld hl, wBattleMonStatus
+	ld de, wPlayerStatsToDouble
+	ldh a, [hWhoseTurn]
+	and a
+	jr z, .checkburn
+	ld hl, wEnemyMonStatus
+	ld de, wEnemyStatsToDouble
+.checkburn
+	ld a, [hl]		;load statuses
+	and 1 << BRN	;test for burn 
+	jr z, .checkpar
+	ld a, $01
+	ld [de], a	;set attack to be doubled to undo the stat change of BRN
+	call DoubleSelectedStats
+	jr .return
+.checkpar
+	ld a, [hl]		;load statuses
+	and 1 << PAR	;test for paralyze 
+	jr z, .return
+	ld a, $04
+	ld [de], a	;set speed to be doubled (done twice) to undo the stat change of BRN
+	call DoubleSelectedStats
+	call DoubleSelectedStats
+.return
+	xor a
+	ld [de], a	;reset the stat change bits
+	ret
+
+; Reused for pureRGB AI
 DoubleSelectedStats:
 	ldh a, [hWhoseTurn]
 	and a
@@ -18,7 +51,6 @@ DoubleSelectedStats:
 	dec c
 	ret z
 	jr .loop
-
 .doubleStat
 	ld a, [hl]
 	add a
@@ -29,34 +61,34 @@ DoubleSelectedStats:
 	ret
 
 ; does nothing since no stats are ever selected (barring glitches)
-HalveSelectedStats:
-	ldh a, [hWhoseTurn]
-	and a
-	ld a, [wPlayerStatsToHalve]
-	ld hl, wBattleMonAttack
-	jr z, .notEnemyTurn
-	ld a, [wEnemyStatsToHalve]
-	ld hl, wEnemyMonAttack
-.notEnemyTurn
-	ld c, 4
-	ld b, a
-.loop
-	srl b
-	call c, .halveStat
-	inc hl
-	inc hl
-	dec c
-	ret z
-	jr .loop
+;HalveSelectedStats:
+;	ldh a, [hWhoseTurn]
+;	and a
+;	ld a, [wPlayerStatsToHalve]
+;	ld hl, wBattleMonAttack
+;	jr z, .notEnemyTurn
+;	ld a, [wEnemyStatsToHalve]
+;	ld hl, wEnemyMonAttack
+;.notEnemyTurn
+;	ld c, 4
+;	ld b, a
+;.loop
+;	srl b
+;	call c, .halveStat
+;	inc hl
+;	inc hl
+;	dec c
+;	ret z
+;	jr .loop
 
-.halveStat
-	ld a, [hl]
-	srl a
-	ld [hli], a
-	rr [hl]
-	or [hl]
-	jr nz, .nonzeroStat
-	ld [hl], 1
-.nonzeroStat
-	dec hl
-	ret
+;.halveStat
+;	ld a, [hl]
+;	srl a
+;	ld [hli], a
+;	rr [hl]
+;	or [hl]
+;	jr nz, .nonzeroStat
+;	ld [hl], 1
+;.nonzeroStat
+	;dec hl
+;	ret