diff --git a/data/battle_scripts_1.s b/data/battle_scripts_1.s
index e9d019e43..e4c628d76 100644
--- a/data/battle_scripts_1.s
+++ b/data/battle_scripts_1.s
@@ -5925,6 +5925,7 @@ BattleScript_PayDayMoneyAndPickUpItems::
 	end2
 
 BattleScript_LocalBattleLost::
+	jumpifbattletype BATTLE_TYPE_INGAME_PARTNER, BattleScript_LocalBattleLostPrintWhiteOut
 	jumpifbattletype BATTLE_TYPE_DOME, BattleScript_CheckDomeDrew
 	jumpifbattletype BATTLE_TYPE_FRONTIER, BattleScript_LocalBattleLostPrintTrainersWinText
 	jumpifbattletype BATTLE_TYPE_TRAINER_HILL, BattleScript_LocalBattleLostPrintTrainersWinText
diff --git a/include/constants/battle_config.h b/include/constants/battle_config.h
index 29b7b5750..65f85af95 100644
--- a/include/constants/battle_config.h
+++ b/include/constants/battle_config.h
@@ -226,8 +226,9 @@
 #define B_LAST_USED_BALL            TRUE     // If TRUE, the "last used ball" feature from Gen 7 will be implemented
 #define B_LAST_USED_BALL_BUTTON     R_BUTTON // If last used ball is implemented, this button (or button combo) will trigger throwing the last used ball.
 
-// Other
-#define B_DOUBLE_WILD_CHANCE        0     // % chance of encountering two Pokémon in a Wild Encounter.
+// Other settings
+#define B_DOUBLE_WILD_CHANCE                0    // % chance of encountering two Pokémon in a Wild Encounter.
+#define B_NEW_MULTI_BATTLE_DEFEAT_CONDITION TRUE // In Gen5+, multi battles end when the Player and also their Partner don't have any more Pokémon to fight.
 
 // Animation Settings
 #define B_NEW_SWORD_PARTICLE            FALSE    // If set to TRUE, it updates Swords Dance's particle.
diff --git a/src/battle_script_commands.c b/src/battle_script_commands.c
index f5fb72e68..6b1f5a6ff 100644
--- a/src/battle_script_commands.c
+++ b/src/battle_script_commands.c
@@ -4113,6 +4113,28 @@ static void Cmd_getexp(void)
     }
 }
 
+#ifdef B_NEW_MULTI_BATTLE_DEFEAT_CONDITION == TRUE
+static bool32 NoAliveMonsForPlayerAndPartner(void)
+{
+    u32 i;
+    u32 HP_count = 0;
+
+    if (gBattleTypeFlags & BATTLE_TYPE_INGAME_PARTNER && (gPartnerTrainerId == TRAINER_STEVEN_PARTNER || gPartnerTrainerId >= TRAINER_CUSTOM_PARTNER))
+    {
+        for (i = 0; i < PARTY_SIZE; i++)
+        {
+            if (GetMonData(&gPlayerParty[i], MON_DATA_SPECIES) && !GetMonData(&gPlayerParty[i], MON_DATA_IS_EGG)
+             && (!(gBattleTypeFlags & BATTLE_TYPE_ARENA) || !(gBattleStruct->arenaLostPlayerMons & gBitTable[i])))
+            {
+                HP_count += GetMonData(&gPlayerParty[i], MON_DATA_HP);
+            }
+        }
+    }
+
+    return (HP_count == 0);
+}
+#endif
+
 static bool32 NoAliveMonsForPlayer(void)
 {
     u32 i;
@@ -4168,7 +4190,11 @@ static void Cmd_unknown_24(void)
     if (gBattleControllerExecFlags)
         return;
 
-    if (NoAliveMonsForPlayer())
+    #ifdef B_NEW_MULTI_BATTLE_DEFEAT_CONDITION == TRUE
+    if (gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_INGAME_PARTNER) && NoAliveMonsForPlayerAndPartner())
+        gBattleOutcome |= B_OUTCOME_LOST;
+    #endif
+    if (!(gBattleTypeFlags & (BATTLE_TYPE_MULTI | BATTLE_TYPE_INGAME_PARTNER)) && NoAliveMonsForPlayer())
         gBattleOutcome |= B_OUTCOME_LOST;
     if (NoAliveMonsForOpponent())
         gBattleOutcome |= B_OUTCOME_WON;