Improve AI's setup logic (#7345)

src/battle_ai_util.c

@@ -1443,6 +1443,26 @@ bool32 CanAIFaintTarget(u32 battlerAtk, u32 battlerDef, u32 numHits)
     return FALSE;
 }
 
+// Can battler KO the target ignoring any Endure effects (Sturdy, Focus Sash, etc.)
+bool32 CanBattlerKOTargetIgnoringSturdy(u32 battlerAtk, u32 battlerDef)
+{
+    struct AiLogicData *aiData = gAiLogicData;
+    s32 moveIndex, dmg;
+    u16 *moves = GetMovesArray(battlerAtk);
+    u32 moveLimitations = aiData->moveLimitations[battlerAtk];
+
+    for (moveIndex = 0; moveIndex < MAX_MON_MOVES; moveIndex++)
+    {
+        if (IsMoveUnusable(moveIndex, moves[moveIndex], moveLimitations))
+            continue;
+        dmg = AI_GetDamage(battlerAtk, battlerDef, moveIndex, AI_ATTACKING, aiData);
+
+        if (gBattleMons[battlerDef].hp <= dmg && CanEndureHit(battlerAtk, battlerDef, moves[moveIndex]))
+            return TRUE;
+    }
+    return FALSE;
+}
+
 bool32 CanTargetMoveFaintAi(u32 move, u32 battlerDef, u32 battlerAtk, u32 nHits)
 {
     u32 indexSlot = GetMoveSlot(GetMovesArray(battlerDef), move);
@@ -4220,6 +4240,35 @@ bool32 IsRecycleEncouragedItem(u32 item)
     return FALSE;
 }
 
+bool32 HasMoveThatChangesKOThreshold(u32 battlerId, u32 noOfHitsToFaint, u32 aiIsFaster)
+{
+    s32 i;
+    u16 *moves = GetMovesArray(battlerId);
+
+    for (i = 0; i < MAX_MON_MOVES; i++)
+    {
+        if (moves[i] == MOVE_NONE || moves[i] == MOVE_UNAVAILABLE)
+            continue;
+        if (noOfHitsToFaint <= 2)
+        {
+            if (GetMovePriority(moves[i]) > 0)
+                return TRUE;
+
+            switch (gMovesInfo[moves[i]].additionalEffects[i].moveEffect)
+            {
+                case MOVE_EFFECT_SPD_MINUS_1:
+                case MOVE_EFFECT_SPD_MINUS_2:
+                {
+                    if(aiIsFaster)
+                        return TRUE;
+                }
+            }
+        }
+    }
+
+    return FALSE;
+}
+
 static enum AIScore IncreaseStatUpScoreInternal(u32 battlerAtk, u32 battlerDef, enum StatChange statId, bool32 considerContrary)
 {
     enum AIScore tempScore = NO_INCREASE;
@@ -4268,6 +4317,14 @@ static enum AIScore IncreaseStatUpScoreInternal(u32 battlerAtk, u32 battlerDef,
         || HasBattlerSideMoveWithAdditionalEffect(battlerDef, MOVE_EFFECT_HAZE)))
         return NO_INCREASE;
 
+    // Don't increase stats if AI could KO target through Sturdy effect, as otherwise it always 2HKOs
+    if (CanBattlerKOTargetIgnoringSturdy(battlerAtk, battlerDef))
+        return NO_INCREASE;
+
+    // Don't increase stats if player has a move that can change the KO threshold
+    if (HasMoveThatChangesKOThreshold(battlerDef, noOfHitsToFaint, aiIsFaster))
+        return NO_INCREASE;
+
     // Predicting switch
     if (IsBattlerPredictedToSwitch(battlerDef))
     {

test/battle/ai/ai.c

@@ -923,3 +923,25 @@ AI_SINGLE_BATTLE_TEST("AI will prefer resisted move over failing move")
         TURN { MOVE(player, MOVE_ABSORB); EXPECT_MOVE(opponent, MOVE_MEGA_DRAIN);}
     }
 }
+
+AI_SINGLE_BATTLE_TEST("AI won't setup if it can KO through Sturdy effect")
+{
+    GIVEN {
+        AI_FLAGS(AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_CHECK_VIABILITY | AI_FLAG_TRY_TO_FAINT | AI_FLAG_OMNISCIENT);
+        PLAYER(SPECIES_SKARMORY) { Ability(ABILITY_STURDY); Moves(MOVE_TACKLE); }
+        OPPONENT(SPECIES_MOLTRES) { Moves(MOVE_FIRE_BLAST, MOVE_AGILITY); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_TACKLE); EXPECT_MOVE(opponent, MOVE_FIRE_BLAST); }
+    }
+}
+
+AI_SINGLE_BATTLE_TEST("AI won't setup if otherwise good scenario is changed by the presence of priority")
+{
+    GIVEN {
+        AI_FLAGS(AI_FLAG_CHECK_BAD_MOVE | AI_FLAG_CHECK_VIABILITY | AI_FLAG_TRY_TO_FAINT | AI_FLAG_OMNISCIENT);
+        PLAYER(SPECIES_FLOATZEL) { Speed(2); Moves(MOVE_AQUA_JET, MOVE_SURF); }
+        OPPONENT(SPECIES_DONPHAN) { Speed(5); Moves(MOVE_BULK_UP, MOVE_EARTHQUAKE); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_SURF); EXPECT_MOVE(opponent, MOVE_EARTHQUAKE); }
+    }
+}