Fix Baton Pass breaking on Memento

src/battle_main.c

@@ -3677,8 +3677,8 @@ const u8* FaintClearSetData(u32 battler)
     gBattleStruct->zmove.toBeUsed[battler] = MOVE_NONE;
     gBattleStruct->zmove.effect = EFFECT_HIT;
     // Clear Dynamax data
-    UndoDynamax(battler);	
-	
+    UndoDynamax(battler);
+
     return result;
 }
 
@@ -5835,7 +5835,7 @@ static void TryEvolvePokemon(void)
             sTriedEvolving |= gBitTable[i];
 
             if (species == SPECIES_NONE && (gLeveledUpInBattle & gBitTable[i]))
-            { 
+            {
                 gLeveledUpInBattle &= ~(gBitTable[i]);
                 species = GetEvolutionTargetSpecies(&gPlayerParty[i], EVO_MODE_BATTLE_ONLY, gLeveledUpInBattle, NULL);
             }

src/battle_script_commands.c

@@ -2106,7 +2106,7 @@ static void Cmd_adjustdamage(void)
         gLastUsedItem = gBattleMons[gBattlerTarget].item;
         gSpecialStatuses[gBattlerTarget].focusBanded = FALSE;
         gSpecialStatuses[gBattlerTarget].focusSashed = FALSE;
-        
+
     }
     else if (gSpecialStatuses[gBattlerTarget].sturdied)
     {
@@ -3225,8 +3225,8 @@ void SetMoveEffect(bool32 primary, bool32 certain)
                 {
                     gBattleMons[gEffectBattler].status2 |= sStatusFlagsForMoveEffects[gBattleScripting.moveEffect];
                     gBattlescriptCurrInstr++;
-                } 
-                else 
+                }
+                else
                 {
                     gBattlescriptCurrInstr++;
                 }
@@ -6285,7 +6285,7 @@ static void Cmd_moveend(void)
                         break;
                     }
                 }
-                
+
                 if (!(gBattleStruct->lastMoveFailed & gBitTable[gBattlerAttacker]
                     || (!gSpecialStatuses[gBattlerAttacker].dancerUsedMove
                         && gBattleStruct->bouncedMoveIsUsed)))
@@ -7030,8 +7030,12 @@ static void Cmd_openpartyscreen(void)
                 if (gAbsentBattlerFlags & gBitTable[battlerOpposite])
                     battlerOpposite ^= BIT_FLANK;
 
-                BtlController_EmitLinkStandbyMsg(battlerOpposite, BUFFER_A, LINK_STANDBY_MSG_ONLY, FALSE);
-                MarkBattlerForControllerExec(battlerOpposite);
+                // Make sure we're checking a valid battler. In edge case scenarios - battler could be absent and battlerOpposite would become a non-existent one softlocking the game.
+                if (battlerOpposite < gBattlersCount)
+                {
+                    BtlController_EmitLinkStandbyMsg(battlerOpposite, BUFFER_A, LINK_STANDBY_MSG_ONLY, FALSE);
+                    MarkBattlerForControllerExec(battlerOpposite);
+                }
             }
         }
     }

test/battle/move_effect/baton_pass.c

@@ -1,6 +1,30 @@
 #include "global.h"
 #include "test/battle.h"
 
+ASSUMPTIONS
+{
+    ASSUME(gMovesInfo[MOVE_BATON_PASS].effect == EFFECT_BATON_PASS);
+}
+
+// This softlocked the game before.
+SINGLE_BATTLE_TEST("Baton Pass used after Memento works correctly")
+{
+    GIVEN {
+        PLAYER(SPECIES_WOBBUFFET);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_WYNAUT);
+        OPPONENT(SPECIES_CATERPIE);
+    } WHEN {
+        TURN { MOVE(player, MOVE_MEMENTO); SEND_OUT(player, 1); MOVE(opponent, MOVE_BATON_PASS); SEND_OUT(opponent, 1); }
+    } SCENE {
+        MESSAGE("Wobbuffet used Memento!");
+        MESSAGE("Wobbuffet fainted!");
+        MESSAGE("Foe Wynaut used Baton Pass!");
+        MESSAGE("2 sent out Caterpie!");
+        MESSAGE("Go! Wobbuffet!");
+    }
+}
+
 TO_DO_BATTLE_TEST("Baton Pass switches out the user");
 TO_DO_BATTLE_TEST("Baton Pass fails if there's no valid party Pokémon left");
 TO_DO_BATTLE_TEST("Baton Pass passes both positive and negative stat changes");