Fix Beat Up's battle script to avoid an out-of-bounds array access

asm/macros/battle_script.inc

@@ -1022,7 +1022,7 @@
 	.4byte \ptr
 	.endm
 
-	.macro trydobeatup endPtr:req, failPtr:req
+	.macro trydobeatup endPtr=NULL, failPtr=NULL
 	.byte 0xc4
 	.4byte \endPtr
 	.4byte \failPtr

data/battle_scripts_1.s

@@ -5183,10 +5183,18 @@ BattleScript_EffectTeleportNew:
 BattleScript_EffectTeleportNewEnd:
 	goto BattleScript_MoveEnd
 
-.if B_BEAT_UP < GEN_5
 BattleScript_EffectBeatUp::
 	attackcanceler
 	accuracycheck BattleScript_PrintMoveMissed, ACC_CURR_MOVE
+.if B_BEAT_UP >= GEN_5
+	attackstring
+	ppreduce
+	critcalc
+	damagecalc
+	adjustdamage
+	trydobeatup
+	goto BattleScript_HitFromAtkAnimation
+.else
 	attackstring
 	pause B_WAIT_TIME_SHORT
 	ppreduce
@@ -5216,12 +5224,6 @@ BattleScript_BeatUpAttack::
 	goto BattleScript_BeatUpLoop
 BattleScript_BeatUpEnd::
 	end
-.else
-BattleScript_EffectBeatUp::
-	attackcanceler
-	accuracycheck BattleScript_PrintMoveMissed, ACC_CURR_MOVE
-	addbyte gBattleCommunication, 1
-	goto BattleScript_HitFromAtkString
 .endif
 
 BattleScript_EffectSemiInvulnerable::

include/battle.h

@@ -650,6 +650,7 @@ struct BattleStruct
     u8 skyDropTargets[MAX_BATTLERS_COUNT]; // For Sky Drop, to account for if multiple Pokemon use Sky Drop in a double battle.
     // When using a move which hits multiple opponents which is then bounced by a target, we need to make sure, the move hits both opponents, the one with bounce, and the one without.
     u8 attackerBeforeBounce:2;
+    u8 beatUpSlot:3;
     u8 targetsDone[MAX_BATTLERS_COUNT]; // Each battler as a bit.
     u16 overwrittenAbilities[MAX_BATTLERS_COUNT];    // abilities overwritten during battle (keep separate from battle history in case of switching)
 };

src/battle_main.c

@@ -3039,6 +3039,7 @@ static void BattleStartClearSetData(void)
 
     gBattleStruct->stickyWebUser = 0xFF;
     gBattleStruct->appearedInBattle = 0;
+    gBattleStruct->beatUpSlot = 0;
 
     for (i = 0; i < PARTY_SIZE; i++)
     {

src/battle_script_commands.c

@@ -12855,6 +12855,10 @@ static void Cmd_trysetfutureattack(void)
 
 static void Cmd_trydobeatup(void)
 {
+#if B_BEAT_UP >= GEN_5
+    gBattleStruct->beatUpSlot++;
+    gBattlescriptCurrInstr += 9;
+#else
     struct Pokemon *party;
 
     if (GetBattlerSide(gBattlerAttacker) == B_SIDE_PLAYER)
@@ -12898,6 +12902,7 @@ static void Cmd_trydobeatup(void)
         else
             gBattlescriptCurrInstr = T1_READ_PTR(gBattlescriptCurrInstr + 5);
     }
+#endif
 }
 
 static void Cmd_setsemiinvulnerablebit(void)

src/battle_util.c

@@ -230,8 +230,9 @@ static u8 CalcBeatUpPower(void)
         party = gPlayerParty;
     else
         party = gEnemyParty;
-    // Party slot is set in the battle script for Beat Up
+
-    species = GetMonData(&party[gBattleCommunication[0] - 1], MON_DATA_SPECIES);
+    // Party slot is incremented by the battle script for Beat Up after this damage calculation
+    species = GetMonData(&party[gBattleStruct->beatUpSlot], MON_DATA_SPECIES);
     basePower = (gSpeciesInfo[species].baseAttack / 10) + 5;
 
     return basePower;
@@ -3875,7 +3876,7 @@ u8 AtkCanceller_UnableToUseMove(void)
                         gMultiHitCounter++;
                 }
 
-                gBattleCommunication[0] = 0; // For later
+                gBattleStruct->beatUpSlot = 0;
                 PREPARE_BYTE_NUMBER_BUFFER(gBattleScripting.multihitString, 1, 0)
             }
             #endif