Fix AI switching in absorbing mon incorrectly

include/battle.h

@@ -818,6 +818,7 @@ struct BattleStruct
     u8 pursuitSwitchByMove:1;
     u8 pursuitStoredSwitch; // Stored id for the Pursuit target's switch
     s32 battlerExpReward;
+    u16 prevTurnSpecies[MAX_BATTLERS_COUNT]; // Stores species the AI has in play at start of turn
 
     // Simultaneous hp reduction for spread moves
     s32 moveDamage[MAX_BATTLERS_COUNT];

src/battle_ai_switch_items.c

@@ -348,6 +348,9 @@ static bool32 FindMonThatAbsorbsOpponentsMove(u32 battler)
 
     if (!(AI_THINKING_STRUCT->aiFlags[GetThinkingBattler(battler)] & AI_FLAG_SMART_SWITCHING))
         return FALSE;
+    if (gBattleStruct->prevTurnSpecies[battler] != gBattleMons[battler].species) // AI mon has changed, player's behaviour no longer reliable; note to override this if using AI_FLAG_PREDICT_MOVE
+        return FALSE; 
+
     if (HasSuperEffectiveMoveAgainstOpponents(battler, TRUE) && (RandomPercentage(RNG_AI_SWITCH_ABSORBING, 66) || AI_DATA->aiSwitchPredictionInProgress))
         return FALSE;
 

src/battle_main.c

@@ -4158,6 +4158,7 @@ void SetupAISwitchingData(u32 battler, enum SwitchType switchType)
         if (ShouldSwitch(opposingBattler))
             AI_DATA->shouldSwitch |= (1u << opposingBattler);
         AI_DATA->aiSwitchPredictionInProgress = FALSE;
+        gBattleStruct->prevTurnSpecies[opposingBattler] = gBattleMons[opposingBattler].species;
 
         // Determine whether AI will use predictions this turn
         AI_DATA->predictingSwitch = RandomPercentage(RNG_AI_PREDICT_SWITCH, 50);
@@ -4167,6 +4168,7 @@ void SetupAISwitchingData(u32 battler, enum SwitchType switchType)
     AI_DATA->mostSuitableMonId[battler] = GetMostSuitableMonToSwitchInto(battler, switchType);
     if (ShouldSwitch(battler))
         AI_DATA->shouldSwitch |= (1u << battler);
+    gBattleStruct->prevTurnSpecies[battler] = gBattleMons[battler].species;
 }
 
 static void HandleTurnActionSelectionState(void)

test/battle/ai/ai_switching.c

@@ -1026,3 +1026,17 @@ AI_SINGLE_BATTLE_TEST("Switch AI: AI won't switch in ace mon after U-Turn if oth
             TURN { EXPECT_MOVE(opponent, MOVE_U_TURN); EXPECT_SEND_OUT(opponent, 2); MOVE(player, MOVE_SURF); }
     }
 }
+
+AI_SINGLE_BATTLE_TEST("AI_FLAG_SMART_SWITCHING: AI won't switch in absorbing mon immediately after sending out new mon")
+{
+    GIVEN {
+        AI_FLAGS(AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_TRY_TO_FAINT | AI_FLAG_CHECK_VIABILITY | AI_FLAG_SMART_SWITCHING | AI_FLAG_SMART_MON_CHOICES | AI_FLAG_OMNISCIENT);
+        PLAYER(SPECIES_BLAZIKEN) { Moves(MOVE_FLAMETHROWER, MOVE_CLOSE_COMBAT); }
+        OPPONENT(SPECIES_FERROTHORN) { Moves(MOVE_GYRO_BALL); }
+        OPPONENT(SPECIES_DIALGA) { Moves(MOVE_DRACO_METEOR); }
+        OPPONENT(SPECIES_HEATRAN) { Moves(MOVE_EARTH_POWER, MOVE_FLAMETHROWER); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_FLAMETHROWER); EXPECT_SEND_OUT(opponent, 1); }
+        TURN { MOVE(player, MOVE_CLOSE_COMBAT); EXPECT_MOVE(opponent, MOVE_DRACO_METEOR); }
+    }
+}