New feature - battle 2 vs 1 opponent

data/maps/EverGrandeCity_PokemonLeague_1F/scripts.inc

@@ -48,7 +48,7 @@ EverGrandeCity_PokemonLeague_1F_Pokemart_229624: @ 8229624
 EverGrandeCity_PokemonLeague_1F_EventScript_229636:: @ 8229636
 	special SavePlayerParty
 		
-	trainerbattle 10, TRAINER_ALBERT, 0, NULL, EverGrandeCity_PokemonLeague_1F_Text_2296E8
+	trainerbattle 10, TRAINER_WALLACE, 0, NULL, EverGrandeCity_PokemonLeague_1F_Text_2296E8
 	trainerbattle 11, TRAINER_ALEXA, 0, NULL, EverGrandeCity_PokemonLeague_1F_Text_2297EF
 	
 	setvar VAR_0x8004, SPECIAL_BATTLE_MULTI

include/battle_ai_switch_items.h

@@ -11,6 +11,7 @@ enum
     AI_ITEM_NOT_RECOGNIZABLE
 };
 
+void GetAIPartyIndexes(u32 battlerId, s32 *firstId, s32 *lastId);
 void AI_TrySwitchOrUseItem(void);
 u8 GetMostSuitableMonToSwitchInto(void);
 

include/constants/battle.h

@@ -80,6 +80,7 @@
 #define BATTLE_TYPE_FRONTIER_NO_PYRAMID     (BATTLE_TYPE_BATTLE_TOWER | BATTLE_TYPE_DOME | BATTLE_TYPE_PALACE | BATTLE_TYPE_ARENA | BATTLE_TYPE_FACTORY | BATTLE_TYPE_PIKE)
 
 #define WILD_DOUBLE_BATTLE ((gBattleTypeFlags & BATTLE_TYPE_DOUBLE && !(gBattleTypeFlags & (BATTLE_TYPE_LINK | BATTLE_TYPE_TRAINER))))
+#define BATTLE_TWO_VS_ONE_OPPONENT ((gBattleTypeFlags & BATTLE_TYPE_INGAME_PARTNER && gTrainerBattleOpponent_B == 0xFFFF))
 
 // Battle Outcome defines
 #define B_OUTCOME_WON                  0x1

src/battle_ai_switch_items.c

@@ -2,6 +2,7 @@
 #include "battle.h"
 #include "battle_ai_script_commands.h"
 #include "battle_controllers.h"
+#include "battle_setup.h"
 #include "pokemon.h"
 #include "random.h"
 #include "util.h"
@@ -15,6 +16,25 @@ static bool8 HasSuperEffectiveMoveAgainstOpponents(bool8 noRng);
 static bool8 FindMonWithFlagsAndSuperEffective(u16 flags, u8 moduloPercent);
 static bool8 ShouldUseItem(void);
 
+void GetAIPartyIndexes(u32 battlerId, s32 *firstId, s32 *lastId)
+{
+    if (BATTLE_TWO_VS_ONE_OPPONENT && (battlerId & BIT_SIDE) == B_SIDE_OPPONENT)
+    {
+        *firstId = 0, *lastId = 6;
+    }
+    else if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_INGAME_PARTNER | BATTLE_TYPE_x800000))
+    {
+        if ((battlerId & BIT_FLANK) == B_FLANK_LEFT)
+            *firstId = 0, *lastId = 3;
+        else
+            *firstId = 3, *lastId = 6;
+    }
+    else
+    {
+        *firstId = 0, *lastId = 6;
+    }
+}
+
 static bool8 ShouldSwitchIfPerishSong(void)
 {
     if (gStatuses3[gActiveBattler] & STATUS3_PERISH_SONG
@@ -60,17 +80,7 @@ static bool8 ShouldSwitchIfWonderGuard(void)
     }
 
     // Get party information.
-    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    GetAIPartyIndexes(gActiveBattler, &firstId, &lastId);
-    {
-        if ((gActiveBattler & BIT_FLANK) == B_FLANK_LEFT)
-            firstId = 0, lastId = 3;
-        else
-            firstId = 3, lastId = 6;
-    }
-    else
-    {
-        firstId = 0, lastId = 6;
-    }
 
     if (GetBattlerSide(gActiveBattler) == B_SIDE_PLAYER)
         party = gPlayerParty;
@@ -152,17 +162,7 @@ static bool8 FindMonThatAbsorbsOpponentsMove(void)
     if (gBattleMons[gActiveBattler].ability == absorbingTypeAbility)
         return FALSE;
 
-    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    GetAIPartyIndexes(gActiveBattler, &firstId, &lastId);
-    {
-        if ((gActiveBattler & BIT_FLANK) == B_FLANK_LEFT)
-            firstId = 0, lastId = 3;
-        else
-            firstId = 3, lastId = 6;
-    }
-    else
-    {
-        firstId = 0, lastId = 6;
-    }
 
     if (GetBattlerSide(gActiveBattler) == B_SIDE_PLAYER)
         party = gPlayerParty;
@@ -343,17 +343,7 @@ static bool8 FindMonWithFlagsAndSuperEffective(u16 flags, u8 moduloPercent)
         battlerIn2 = gActiveBattler;
     }
 
-    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    GetAIPartyIndexes(gActiveBattler, &firstId, &lastId);
-    {
-        if ((gActiveBattler & BIT_FLANK) == 0)
-            firstId = 0, lastId = 3;
-        else
-            firstId = 3, lastId = 6;
-    }
-    else
-    {
-        firstId = 0, lastId = 6;
-    }
 
     if (GetBattlerSide(gActiveBattler) == B_SIDE_PLAYER)
         party = gPlayerParty;
@@ -453,17 +443,7 @@ static bool8 ShouldSwitch(void)
         battlerIn2 = *activeBattlerPtr;
     }
 
-    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    GetAIPartyIndexes(gActiveBattler, &firstId, &lastId);
-    {
-        if ((gActiveBattler & BIT_FLANK) == B_FLANK_LEFT)
-            firstId = 0, lastId = 3;
-        else
-            firstId = 3, lastId = 6;
-    }
-    else
-    {
-        firstId = 0, lastId = 6;
-    }
 
     if (GetBattlerSide(gActiveBattler) == B_SIDE_PLAYER)
         party = gPlayerParty;
@@ -544,17 +524,7 @@ void AI_TrySwitchOrUseItem(void)
                         battlerIn2 = GetBattlerAtPosition(battlerIdentity ^ BIT_FLANK);
                     }
 
-                    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+                    GetAIPartyIndexes(gActiveBattler, &firstId, &lastId);
-                    {
-                        if ((gActiveBattler & BIT_FLANK) == B_FLANK_LEFT)
-                            firstId = 0, lastId = 3;
-                        else
-                            firstId = 3, lastId = 6;
-                    }
-                    else
-                    {
-                        firstId = 0, lastId = 6;
-                    }
 
                     for (monToSwitchId = firstId; monToSwitchId < lastId; monToSwitchId++)
                     {
@@ -626,17 +596,7 @@ u8 GetMostSuitableMonToSwitchInto(void)
         battlerIn2 = gActiveBattler;
     }
 
-    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    GetAIPartyIndexes(gActiveBattler, &firstId, &lastId);
-    {
-        if ((gActiveBattler & BIT_FLANK) == B_FLANK_LEFT)
-            firstId = 0, lastId = 3;
-        else
-            firstId = 3, lastId = 6;
-    }
-    else
-    {
-        firstId = 0, lastId = 6;
-    }
 
     if (GetBattlerSide(gActiveBattler) == B_SIDE_PLAYER)
         party = gPlayerParty;

src/battle_controller_opponent.c

@@ -234,7 +234,7 @@ static void sub_805F2F0(void)
     bool8 var = FALSE;
     bool8 var2;
 
-    if (!IsDoubleBattle() || ((IsDoubleBattle() && (gBattleTypeFlags & BATTLE_TYPE_MULTI)) || (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS)))
+    if (!IsDoubleBattle() || ((IsDoubleBattle() && (gBattleTypeFlags & BATTLE_TYPE_MULTI) && !BATTLE_TWO_VS_ONE_OPPONENT) || (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS)))
     {
         if (gSprites[gHealthboxSpriteIds[gActiveBattler]].callback == SpriteCallbackDummy)
             var = TRUE;
@@ -297,13 +297,13 @@ static void sub_805F560(void)
 
     if (!gBattleSpritesDataPtr->healthBoxesData[gActiveBattler].flag_x80 && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler].ballAnimActive && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler].field_1_x1)
         sub_8172EF0(gActiveBattler, &gEnemyParty[gBattlerPartyIndexes[gActiveBattler]]);
-    if (!(gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS) && !(gBattleTypeFlags & BATTLE_TYPE_MULTI) && IsDoubleBattle() && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler ^ BIT_FLANK].flag_x80 && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler ^ BIT_FLANK].ballAnimActive && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler ^ BIT_FLANK].field_1_x1)
+    if (!(gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS) && (!(gBattleTypeFlags & BATTLE_TYPE_MULTI) || BATTLE_TWO_VS_ONE_OPPONENT) && IsDoubleBattle() && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler ^ BIT_FLANK].flag_x80 && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler ^ BIT_FLANK].ballAnimActive && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler ^ BIT_FLANK].field_1_x1)
         sub_8172EF0(gActiveBattler ^ BIT_FLANK, &gEnemyParty[gBattlerPartyIndexes[gActiveBattler ^ BIT_FLANK]]);
     if (!gBattleSpritesDataPtr->healthBoxesData[gActiveBattler].ballAnimActive && !gBattleSpritesDataPtr->healthBoxesData[gActiveBattler ^ BIT_FLANK].ballAnimActive)
     {
         if (!gBattleSpritesDataPtr->healthBoxesData[gActiveBattler].field_1_x80)
         {
-            if (IsDoubleBattle() && !(gBattleTypeFlags & BATTLE_TYPE_MULTI))
+            if (IsDoubleBattle() && (!(gBattleTypeFlags & BATTLE_TYPE_MULTI) || BATTLE_TWO_VS_ONE_OPPONENT))
             {
                 UpdateHealthboxAttribute(gHealthboxSpriteIds[gActiveBattler ^ BIT_FLANK], &gEnemyParty[gBattlerPartyIndexes[gActiveBattler ^ BIT_FLANK]], HEALTHBOX_ALL);
                 sub_8076918(gActiveBattler ^ BIT_FLANK);
@@ -335,7 +335,7 @@ static void sub_805F560(void)
         sp = TRUE;
     }
 
-    if (!IsDoubleBattle() || (IsDoubleBattle() && (gBattleTypeFlags & BATTLE_TYPE_MULTI)))
+    if (!IsDoubleBattle() || (IsDoubleBattle() && gBattleTypeFlags & BATTLE_TYPE_MULTI && !BATTLE_TWO_VS_ONE_OPPONENT))
     {
         if (gSprites[gUnknown_03005D7C[gActiveBattler]].callback == SpriteCallbackDummy
             && gSprites[gBattlerSpriteIds[gActiveBattler]].callback == SpriteCallbackDummy)
@@ -356,7 +356,7 @@ static void sub_805F560(void)
 
     if (sp && r10)
     {
-        if (IsDoubleBattle() && !(gBattleTypeFlags & BATTLE_TYPE_MULTI))
+        if (IsDoubleBattle() && (!(gBattleTypeFlags & BATTLE_TYPE_MULTI) || BATTLE_TWO_VS_ONE_OPPONENT))
         {
             DestroySprite(&gSprites[gUnknown_03005D7C[gActiveBattler ^ BIT_FLANK]]);
             SetBattlerShadowSpriteCallback(gActiveBattler ^ BIT_FLANK, GetMonData(&gEnemyParty[gBattlerPartyIndexes[gActiveBattler ^ BIT_FLANK]], MON_DATA_SPECIES));
@@ -1278,7 +1278,7 @@ static void OpponentHandleDrawTrainerPic(void)
         trainerPicId = gTrainers[gTrainerBattleOpponent_A].trainerPic;
     }
 
-    if (gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_TWO_OPPONENTS))
+    if (gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_TWO_OPPONENTS) && !BATTLE_TWO_VS_ONE_OPPONENT)
     {
         if ((GetBattlerPosition(gActiveBattler) & BIT_FLANK) != 0) // second mon
             xPos = 152;
@@ -1624,17 +1624,7 @@ static void OpponentHandleChoosePokemon(void)
                 battler2 = GetBattlerAtPosition(B_POSITION_OPPONENT_RIGHT);
             }
 
-            if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+            GetAIPartyIndexes(gActiveBattler, &firstId, &lastId);
-            {
-                if (gActiveBattler == 1)
-                    firstId = 0, lastId = 3;
-                else
-                    firstId = 3, lastId = 6;
-            }
-            else
-            {
-                firstId = 0, lastId = 6;
-            }
 
             for (chosenMonId = firstId; chosenMonId < lastId; chosenMonId++)
             {
@@ -1884,7 +1874,7 @@ static void sub_8062828(u8 taskId)
     u8 savedActiveBank = gActiveBattler;
 
     gActiveBattler = gTasks[taskId].data[0];
-    if (!IsDoubleBattle() || (gBattleTypeFlags & BATTLE_TYPE_MULTI))
+    if ((!IsDoubleBattle() || (gBattleTypeFlags & BATTLE_TYPE_MULTI)) && !BATTLE_TWO_VS_ONE_OPPONENT)
     {
         gBattleResources->bufferA[gActiveBattler][1] = gBattlerPartyIndexes[gActiveBattler];
         sub_80613DC(gActiveBattler, FALSE);

src/battle_controllers.c

@@ -4,6 +4,7 @@
 #include "battle_anim.h"
 #include "battle_controllers.h"
 #include "battle_message.h"
+#include "battle_setup.h"
 #include "cable_club.h"
 #include "link.h"
 #include "party_menu.h"
@@ -153,8 +154,16 @@ static void InitSinglePlayerBtlControllers(void)
 
         gBattlerPartyIndexes[0] = 0;
         gBattlerPartyIndexes[1] = 0;
-        gBattlerPartyIndexes[2] = 3;
+        if (BATTLE_TWO_VS_ONE_OPPONENT)
-        gBattlerPartyIndexes[3] = 3;
+        {
+            gBattlerPartyIndexes[2] = 3;
+            gBattlerPartyIndexes[3] = 1;
+        }
+        else
+        {
+            gBattlerPartyIndexes[2] = 3;
+            gBattlerPartyIndexes[3] = 3;
+        }
     }
     else if (!(gBattleTypeFlags & BATTLE_TYPE_DOUBLE))
     {

src/battle_main.c

@@ -573,7 +573,7 @@ static void CB2_InitBattleInternal(void)
     if (!(gBattleTypeFlags & (BATTLE_TYPE_LINK | BATTLE_TYPE_RECORDED)))
     {
         CreateNPCTrainerParty(&gEnemyParty[0], gTrainerBattleOpponent_A, TRUE);
-        if (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS)
+        if (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS && !BATTLE_TWO_VS_ONE_OPPONENT)
             CreateNPCTrainerParty(&gEnemyParty[3], gTrainerBattleOpponent_B, FALSE);
         SetWildMonHeldItem();
     }
@@ -3245,7 +3245,7 @@ static void DoBattleIntro(void)
             case B_POSITION_OPPONENT_RIGHT:
                 if (gBattleTypeFlags & BATTLE_TYPE_TRAINER)
                 {
-                    if (gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_TWO_OPPONENTS)) // opponent 2 if exists
+                    if (gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_TWO_OPPONENTS) && !BATTLE_TWO_VS_ONE_OPPONENT) // opponent 2 if exists
                     {
                         BtlController_EmitDrawTrainerPic(0);
                         MarkBattlerForControllerExec(gActiveBattler);
@@ -3373,7 +3373,7 @@ static void DoBattleIntro(void)
     case 12: // nothing
         (*state)++;
     case 13: // second opponent's mon send out
-        if (gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_TWO_OPPONENTS))
+        if (gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_TWO_OPPONENTS) && !BATTLE_TWO_VS_ONE_OPPONENT)
         {
             if (gBattleTypeFlags & BATTLE_TYPE_x2000000 && !(gBattleTypeFlags & BATTLE_TYPE_x80000000))
                 gActiveBattler = GetBattlerAtPosition(B_POSITION_PLAYER_RIGHT);

src/battle_message.c

@@ -2302,7 +2302,9 @@ void BufferStringBattle(u16 stringID)
             }
             else
             {
-                if (gBattleTypeFlags & BATTLE_TYPE_INGAME_PARTNER)
+                if (BATTLE_TWO_VS_ONE_OPPONENT)
+                    stringPtr = sText_Trainer1WantsToBattle;
+                else if (gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_INGAME_PARTNER))
                     stringPtr = sText_TwoTrainersWantToBattle;
                 else if (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS)
                     stringPtr = sText_TwoTrainersWantToBattle;
@@ -2345,7 +2347,9 @@ void BufferStringBattle(u16 stringID)
         {
             if (gBattleTypeFlags & BATTLE_TYPE_DOUBLE)
             {
-                if (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS)
+                if (BATTLE_TWO_VS_ONE_OPPONENT)
+                    stringPtr = sText_Trainer1SentOutTwoPkmn;
+                else if (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS)
                     stringPtr = sText_TwoTrainersSentPkmn;
                 else if (gBattleTypeFlags & BATTLE_TYPE_x800000)
                     stringPtr = sText_TwoTrainersSentPkmn;
@@ -2659,7 +2663,7 @@ static const u8 *BattleStringGetOpponentName(u8 *text, u8 multiplayerId, u8 batt
         toCpy = BattleStringGetOpponentNameByTrainerId(gTrainerBattleOpponent_A, text, multiplayerId, battlerId);
         break;
     case B_POSITION_OPPONENT_RIGHT:
-        if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_MULTI))
+        if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_MULTI) && !BATTLE_TWO_VS_ONE_OPPONENT)
             toCpy = BattleStringGetOpponentNameByTrainerId(gTrainerBattleOpponent_B, text, multiplayerId, battlerId);
         else
             toCpy = BattleStringGetOpponentNameByTrainerId(gTrainerBattleOpponent_A, text, multiplayerId, battlerId);
@@ -3098,7 +3102,7 @@ u32 BattleStringExpandPlaceholders(const u8 *src, u8 *dst)
                     toCpy = BattleStringGetOpponentClassByTrainerId(gTrainerBattleOpponent_A);
                     break;
                 case B_POSITION_OPPONENT_RIGHT:
-                    if (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS)
+                    if (gBattleTypeFlags & BATTLE_TYPE_TWO_OPPONENTS && !BATTLE_TWO_VS_ONE_OPPONENT)
                         toCpy = BattleStringGetOpponentClassByTrainerId(gTrainerBattleOpponent_B);
                     else
                         toCpy = BattleStringGetOpponentClassByTrainerId(gTrainerBattleOpponent_A);

src/battle_script_commands.c

@@ -4541,6 +4541,7 @@ static void atk4F_jumpifcantswitch(void)
 {
     s32 i;
     s32 lastMonId;
+    u8 battlerIn1, battlerIn2;
     struct Pokemon *party;
 
     gActiveBattler = GetBattlerForBattleScript(gBattlescriptCurrInstr[1] & ~(ATK4F_DONT_CHECK_STATUSES));
@@ -4551,11 +4552,28 @@ static void atk4F_jumpifcantswitch(void)
     {
         gBattlescriptCurrInstr = T1_READ_PTR(gBattlescriptCurrInstr + 2);
     }
+    else if (BATTLE_TWO_VS_ONE_OPPONENT && GetBattlerSide(gActiveBattler) == B_SIDE_OPPONENT)
+    {
+        battlerIn1 = GetBattlerAtPosition(B_POSITION_OPPONENT_LEFT);
+        battlerIn2 = GetBattlerAtPosition(B_POSITION_OPPONENT_RIGHT);
+        party = gEnemyParty;
+
+        for (i = 0; i < PARTY_SIZE; i++)
+        {
+            if (GetMonData(&party[i], MON_DATA_HP) != 0
+             && GetMonData(&party[i], MON_DATA_SPECIES) != SPECIES_NONE
+             && !GetMonData(&party[i], MON_DATA_IS_EGG)
+             && i != gBattlerPartyIndexes[battlerIn1] && i != gBattlerPartyIndexes[battlerIn2])
+                break;
+        }
+
+        if (i == PARTY_SIZE)
+            gBattlescriptCurrInstr = T1_READ_PTR(gBattlescriptCurrInstr + 2);
+        else
+            gBattlescriptCurrInstr += 6;
+    }
     else if (gBattleTypeFlags & BATTLE_TYPE_INGAME_PARTNER)
     {
-        #ifndef NONMATCHING
-            asm("":::"r5");
-        #endif // NONMATCHING
         if (GetBattlerSide(gActiveBattler) == B_SIDE_OPPONENT)
             party = gEnemyParty;
         else
@@ -4651,8 +4669,6 @@ static void atk4F_jumpifcantswitch(void)
     }
     else
     {
-        u8 battlerIn1, battlerIn2;
-
         if (GetBattlerSide(gActiveBattler) == B_SIDE_OPPONENT)
         {
             battlerIn1 = GetBattlerAtPosition(B_POSITION_OPPONENT_LEFT);
@@ -7952,7 +7968,16 @@ static void atk8F_forcerandomswitch(void)
         else
             party = gEnemyParty;
 
-        if ((gBattleTypeFlags & BATTLE_TYPE_BATTLE_TOWER && gBattleTypeFlags & BATTLE_TYPE_LINK)
+        if (BATTLE_TWO_VS_ONE_OPPONENT && (gBattlerTarget & BIT_SIDE) == B_SIDE_OPPONENT)
+        {
+            firstMonId = 0;
+            lastMonId = 6;
+            monsCount = 6;
+            minNeeded = 2;
+            battler2PartyId = gBattlerPartyIndexes[gBattlerTarget];
+            battler1PartyId = gBattlerPartyIndexes[gBattlerTarget ^ BIT_FLANK];
+        }
+        else if ((gBattleTypeFlags & BATTLE_TYPE_BATTLE_TOWER && gBattleTypeFlags & BATTLE_TYPE_LINK)
             || (gBattleTypeFlags & BATTLE_TYPE_BATTLE_TOWER && gBattleTypeFlags & BATTLE_TYPE_x2000000)
             || (gBattleTypeFlags & BATTLE_TYPE_INGAME_PARTNER))
         {

src/battle_tower.c

@@ -2374,10 +2374,20 @@ void DoSpecialTrainerBattle(void)
         BattleTransition_StartOnField(B_TRANSITION_MAGMA);
         break;
     case SPECIAL_BATTLE_MULTI:
-        if (gSpecialVar_0x8005 & 1)
+        if (gSpecialVar_0x8005 & 1) // Player + AI against wild mon
+        {
             gBattleTypeFlags = BATTLE_TYPE_DOUBLE | BATTLE_TYPE_MULTI | BATTLE_TYPE_INGAME_PARTNER;
+        }
+        else if (gSpecialVar_0x8005 & 2) // Player + AI against one trainer
+        {
+            gTrainerBattleOpponent_B = 0xFFFF;
+            gBattleTypeFlags = BATTLE_TYPE_TRAINER | BATTLE_TYPE_DOUBLE | BATTLE_TYPE_MULTI | BATTLE_TYPE_INGAME_PARTNER;
+        }
         else
+        {
             gBattleTypeFlags = BATTLE_TYPE_TRAINER | BATTLE_TYPE_DOUBLE | BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_MULTI | BATTLE_TYPE_INGAME_PARTNER;
+        }
+
         gPartnerSpriteId = gSpecialVar_0x8007;
         FillPartnerParty(gSpecialVar_0x8006 + TRAINER_CUSTOM_PARTNER);
         gPartnerTrainerId = gSpecialVar_0x8006 + TRAINER_CUSTOM_PARTNER;

src/battle_util.c

@@ -2,6 +2,7 @@
 #include "battle.h"
 #include "battle_controllers.h"
 #include "battle_interface.h"
+#include "battle_setup.h"
 #include "constants/battle_script_commands.h"
 #include "constants/abilities.h"
 #include "constants/moves.h"
@@ -2333,7 +2334,29 @@ bool8 HasNoMonsToSwitch(u8 battler, u8 partyIdBattlerOn1, u8 partyIdBattlerOn2)
     if (!(gBattleTypeFlags & BATTLE_TYPE_DOUBLE))
         return FALSE;
 
-    if (gBattleTypeFlags & BATTLE_TYPE_INGAME_PARTNER)
+    if (BATTLE_TWO_VS_ONE_OPPONENT && GetBattlerSide(battler) == B_SIDE_OPPONENT)
+    {
+        id2 = GetBattlerAtPosition(B_POSITION_OPPONENT_LEFT);
+        id1 = GetBattlerAtPosition(B_POSITION_OPPONENT_RIGHT);
+        party = gEnemyParty;
+
+        if (partyIdBattlerOn1 == PARTY_SIZE)
+            partyIdBattlerOn1 = gBattlerPartyIndexes[id2];
+        if (partyIdBattlerOn2 == PARTY_SIZE)
+            partyIdBattlerOn2 = gBattlerPartyIndexes[id1];
+
+        for (i = 0; i < PARTY_SIZE; i++)
+        {
+            if (GetMonData(&party[i], MON_DATA_HP) != 0
+             && GetMonData(&party[i], MON_DATA_SPECIES2) != SPECIES_NONE
+             && GetMonData(&party[i], MON_DATA_SPECIES2) != SPECIES_EGG
+             && i != partyIdBattlerOn1 && i != partyIdBattlerOn2
+             && i != *(gBattleStruct->monToSwitchIntoId + id2) && i != id1[gBattleStruct->monToSwitchIntoId])
+                break;
+        }
+        return (i == PARTY_SIZE);
+    }
+    else if (gBattleTypeFlags & BATTLE_TYPE_INGAME_PARTNER)
     {
         if (GetBattlerSide(battler) == B_SIDE_PLAYER)
             party = gPlayerParty;