Add RandomChance macro and ability trigger chance config

include/config/battle.h

@@ -147,6 +147,9 @@
 #define B_INTREPID_SWORD            GEN_LATEST // In Gen9+, Intrepid Sword raises Attack by one stage only once per Battle.
 #define B_DAUNTLESS_SHIELD          GEN_LATEST // In Gen9+, Dauntless Shield raises Defense by one stage only once per Battle.
 #define B_DISGUISE_HP_LOSS          GEN_LATEST // In Gen8+, when a Disguised Mimikyu's Disguise is busted, upon changing to its Busted Form it loses HP equal to 1/8 of its maximum HP.
+#define B_ABILITY_TRIGGER_CHANCE    GEN_LATEST // In Gen3, Shed Skin, Cute Charm, Flame Body, Static and Poison Point have a 1/3 chance to trigger. In Gen 4+ it's 30%.
+                                               // In Gen3, Effect Spore has a 10% chance to sleep, poison or paralyze, with an equal chance.
+                                               // In Gen4, it's 30%. In Gen5+ it has 11% to sleep, 9% chance to poison and 10% chance to paralyze.
 
 // Item settings
 #define B_HP_BERRIES                GEN_LATEST // In Gen4+, berries which restore HP activate immediately after HP drops to half. In Gen3, the effect occurs at the end of the turn.

include/random.h

@@ -144,13 +144,16 @@ static inline void Shuffle(void *data, size_t n, size_t size)
  * probability. The array must be known at compile-time (e.g. a global
  * const array).
  *
- * RandomPercentage(tag, t) returns FALSE with probability (1-t)/100,
+ * RandomPercentage(tag, t) returns FALSE with probability 1-t/100,
  * and TRUE with probability t/100.
  *
  * RandomWeighted(tag, w0, w1, ... wN) returns a number from 0 to N
  * inclusive. The return value is proportional to the weights, e.g.
  * RandomWeighted(..., 1, 1) returns 50% 0s and 50% 1s.
- * RandomWeighted(..., 2, 1) returns 2/3 0s and 1/3 1s. */
+ * RandomWeighted(..., 2, 1) returns 2/3 0s and 1/3 1s.
+ *
+ * RandomChance(tag, successes, total) returns FALSE with probability
+ * 1-successes/total, and TRUE with probability successes/total. */
 
 enum RandomTag
 {
@@ -161,6 +164,7 @@ enum RandomTag
     RNG_CUTE_CHARM,
     RNG_DAMAGE_MODIFIER,
     RNG_DIRE_CLAW,
+    RNG_EFFECT_SPORE,
     RNG_FLAME_BODY,
     RNG_FORCE_RANDOM_SWITCH,
     RNG_FROZEN,
@@ -179,6 +183,7 @@ enum RandomTag
     RNG_SECONDARY_EFFECT,
     RNG_SECONDARY_EFFECT_2,
     RNG_SECONDARY_EFFECT_3,
+    RNG_SHED_SKIN,
     RNG_SLEEP_TURNS,
     RNG_SPEED_TIE,
     RNG_STATIC,
@@ -201,6 +206,8 @@ enum RandomTag
         RandomWeightedArray(tag, sum, ARRAY_COUNT(weights), weights); \
     })
 
+#define RandomChance(tag, successes, total) (RandomWeighted(tag, total - successes, successes))
+
 #define RandomPercentage(tag, t) \
     ({ \
         u32 r; \

src/battle_script_commands.c

@@ -1943,7 +1943,7 @@ static void Cmd_critcalc(void)
     else if (critChance == -2)
         gIsCriticalHit = TRUE;
     else
-        gIsCriticalHit = RandomWeighted(RNG_CRITICAL_HIT, sCriticalHitOdds[critChance] - 1, 1);
+        gIsCriticalHit = RandomChance(RNG_CRITICAL_HIT, 1, sCriticalHitOdds[critChance]);
 
     // Counter for EVO_CRITICAL_HITS.
     partySlot = gBattlerPartyIndexes[gBattlerAttacker];

src/battle_util.c

@@ -4861,7 +4861,8 @@ u32 AbilityBattleEffects(u32 caseID, u32 battler, u32 ability, u32 special, u32
                 }
                 break;
             case ABILITY_SHED_SKIN:
-                if ((gBattleMons[battler].status1 & STATUS1_ANY) && (Random() % 3) == 0)
+                if ((gBattleMons[battler].status1 & STATUS1_ANY)
+                 && (B_ABILITY_TRIGGER_CHANCE >= GEN_4 ? RandomPercentage(RNG_SHED_SKIN, 30) : RandomChance(RNG_SHED_SKIN, 1, 3)))
                 {
                 ABILITY_HEAL_MON_STATUS:
                     if (gBattleMons[battler].status1 & (STATUS1_POISON | STATUS1_TOXIC_POISON))
@@ -5502,24 +5503,38 @@ u32 AbilityBattleEffects(u32 caseID, u32 battler, u32 ability, u32 special, u32
             }
             break;
         case ABILITY_EFFECT_SPORE:
-            if (!IS_BATTLER_OF_TYPE(gBattlerAttacker, TYPE_GRASS)
+            if ((!IS_BATTLER_OF_TYPE(gBattlerAttacker, TYPE_GRASS) || B_POWDER_GRASS < GEN_6)
              && GetBattlerAbility(gBattlerAttacker) != ABILITY_OVERCOAT
              && GetBattlerHoldEffect(gBattlerAttacker, TRUE) != HOLD_EFFECT_SAFETY_GOGGLES)
             {
-                i = Random() % 3;
-                if (i == 0)
+                u32 poison, paralysis, sleep;
+
+                if (B_ABILITY_TRIGGER_CHANCE >= GEN_5)
+                {
+                    poison = 9;
+                    paralysis = 19;
+                }
+                else
+                {
+                    poison = 10;
+                    paralysis = 20;
+                }
+                sleep = 30;
+
+                i = RandomUniform(RNG_EFFECT_SPORE, 0, B_ABILITY_TRIGGER_CHANCE >= GEN_4 ? 99 : 299);
+                if (i < poison)
                     goto POISON_POINT;
-                if (i == 1)
+                if (i < paralysis)
                     goto STATIC;
                 // Sleep
-                if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
+                if (i < sleep
+                 && !(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
                  && IsBattlerAlive(gBattlerAttacker)
                  && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
                  && TARGET_TURN_DAMAGED
                  && CanSleep(gBattlerAttacker)
                  && GetBattlerHoldEffect(gBattlerAttacker, TRUE) != HOLD_EFFECT_PROTECTIVE_PADS
-                 && IsMoveMakingContact(move, gBattlerAttacker)
-                 && (Random() % 3) == 0)
+                 && IsMoveMakingContact(move, gBattlerAttacker))
                 {
                     gBattleScripting.moveEffect = MOVE_EFFECT_AFFECTS_USER | MOVE_EFFECT_SLEEP;
                     PREPARE_ABILITY_BUFFER(gBattleTextBuff1, gLastUsedAbility);
@@ -5530,42 +5545,46 @@ u32 AbilityBattleEffects(u32 caseID, u32 battler, u32 ability, u32 special, u32
                 }
             }
             break;
-        POISON_POINT:
         case ABILITY_POISON_POINT:
-            if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
-             && IsBattlerAlive(gBattlerAttacker)
-             && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
-             && TARGET_TURN_DAMAGED
-             && CanBePoisoned(gBattlerTarget, gBattlerAttacker)
-             && GetBattlerHoldEffect(gBattlerAttacker, TRUE) != HOLD_EFFECT_PROTECTIVE_PADS
-             && IsMoveMakingContact(move, gBattlerAttacker)
-             && RandomWeighted(RNG_POISON_POINT, 2, 1))
+            if (B_ABILITY_TRIGGER_CHANCE >= GEN_4 ? RandomPercentage(RNG_POISON_POINT, 30) : RandomChance(RNG_POISON_POINT, 1, 3))
             {
-                gBattleScripting.moveEffect = MOVE_EFFECT_AFFECTS_USER | MOVE_EFFECT_POISON;
-                PREPARE_ABILITY_BUFFER(gBattleTextBuff1, gLastUsedAbility);
-                BattleScriptPushCursor();
-                gBattlescriptCurrInstr = BattleScript_AbilityStatusEffect;
-                gHitMarker |= HITMARKER_STATUS_ABILITY_EFFECT;
-                effect++;
+            POISON_POINT:
+                if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
+                && IsBattlerAlive(gBattlerAttacker)
+                && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
+                && TARGET_TURN_DAMAGED
+                && CanBePoisoned(gBattlerTarget, gBattlerAttacker)
+                && GetBattlerHoldEffect(gBattlerAttacker, TRUE) != HOLD_EFFECT_PROTECTIVE_PADS
+                && IsMoveMakingContact(move, gBattlerAttacker))
+                {
+                    gBattleScripting.moveEffect = MOVE_EFFECT_AFFECTS_USER | MOVE_EFFECT_POISON;
+                    PREPARE_ABILITY_BUFFER(gBattleTextBuff1, gLastUsedAbility);
+                    BattleScriptPushCursor();
+                    gBattlescriptCurrInstr = BattleScript_AbilityStatusEffect;
+                    gHitMarker |= HITMARKER_STATUS_ABILITY_EFFECT;
+                    effect++;
+                }
             }
             break;
-        STATIC:
         case ABILITY_STATIC:
-            if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
-             && IsBattlerAlive(gBattlerAttacker)
-             && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
-             && TARGET_TURN_DAMAGED
-             && CanBeParalyzed(gBattlerAttacker)
-             && GetBattlerHoldEffect(gBattlerAttacker, TRUE) != HOLD_EFFECT_PROTECTIVE_PADS
-             && IsMoveMakingContact(move, gBattlerAttacker)
-             && RandomWeighted(RNG_STATIC, 2, 1))
+            if (B_ABILITY_TRIGGER_CHANCE >= GEN_4 ? RandomPercentage(RNG_STATIC, 30) : RandomChance(RNG_STATIC, 1, 3))
             {
-                gBattleScripting.moveEffect = MOVE_EFFECT_AFFECTS_USER | MOVE_EFFECT_PARALYSIS;
-                PREPARE_ABILITY_BUFFER(gBattleTextBuff1, gLastUsedAbility);
-                BattleScriptPushCursor();
-                gBattlescriptCurrInstr = BattleScript_AbilityStatusEffect;
-                gHitMarker |= HITMARKER_STATUS_ABILITY_EFFECT;
-                effect++;
+            STATIC:
+                if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
+                && IsBattlerAlive(gBattlerAttacker)
+                && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
+                && TARGET_TURN_DAMAGED
+                && CanBeParalyzed(gBattlerAttacker)
+                && GetBattlerHoldEffect(gBattlerAttacker, TRUE) != HOLD_EFFECT_PROTECTIVE_PADS
+                && IsMoveMakingContact(move, gBattlerAttacker))
+                {
+                    gBattleScripting.moveEffect = MOVE_EFFECT_AFFECTS_USER | MOVE_EFFECT_PARALYSIS;
+                    PREPARE_ABILITY_BUFFER(gBattleTextBuff1, gLastUsedAbility);
+                    BattleScriptPushCursor();
+                    gBattlescriptCurrInstr = BattleScript_AbilityStatusEffect;
+                    gHitMarker |= HITMARKER_STATUS_ABILITY_EFFECT;
+                    effect++;
+                }
             }
             break;
         case ABILITY_FLAME_BODY:
@@ -5576,7 +5595,7 @@ u32 AbilityBattleEffects(u32 caseID, u32 battler, u32 ability, u32 special, u32
              && (IsMoveMakingContact(move, gBattlerAttacker))
              && TARGET_TURN_DAMAGED
              && CanBeBurned(gBattlerAttacker)
-             && RandomWeighted(RNG_FLAME_BODY, 2, 1))
+             && (B_ABILITY_TRIGGER_CHANCE >= GEN_4 ? RandomPercentage(RNG_FLAME_BODY, 30) : RandomChance(RNG_FLAME_BODY, 1, 3)))
             {
                 gBattleScripting.moveEffect = MOVE_EFFECT_AFFECTS_USER | MOVE_EFFECT_BURN;
                 PREPARE_ABILITY_BUFFER(gBattleTextBuff1, gLastUsedAbility);
@@ -5592,7 +5611,7 @@ u32 AbilityBattleEffects(u32 caseID, u32 battler, u32 ability, u32 special, u32
              && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
              && TARGET_TURN_DAMAGED
              && IsBattlerAlive(gBattlerTarget)
-             && RandomWeighted(RNG_CUTE_CHARM, 2, 1)
+             && (B_ABILITY_TRIGGER_CHANCE >= GEN_4 ? RandomPercentage(RNG_CUTE_CHARM, 30) : RandomChance(RNG_CUTE_CHARM, 1, 3))
              && !(gBattleMons[gBattlerAttacker].status2 & STATUS2_INFATUATION)
              && AreBattlersOfOppositeGender(gBattlerAttacker, gBattlerTarget)
              && GetBattlerAbility(gBattlerAttacker) != ABILITY_OBLIVIOUS
@@ -5810,7 +5829,7 @@ u32 AbilityBattleEffects(u32 caseID, u32 battler, u32 ability, u32 special, u32
             if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
              && IsBattlerAlive(gBattlerTarget)
              && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
-             && RandomWeighted(RNG_STENCH, 9, 1)
+             && RandomChance(RNG_STENCH, 1, 10)
              && TARGET_TURN_DAMAGED
              && !MoveHasAdditionalEffect(gCurrentMove, MOVE_EFFECT_FLINCH))
             {

test/battle/ability/cute_charm.c

@@ -45,3 +45,22 @@ SINGLE_BATTLE_TEST("Cute Charm cannot infatuate same gender")
         ANIMATION(ANIM_TYPE_MOVE, MOVE_TACKLE, player);
     }
 }
+
+SINGLE_BATTLE_TEST("Cute Charm triggers 30% of the time")
+{
+    PASSES_RANDOMLY(3, 10, RNG_CUTE_CHARM);
+    GIVEN {
+        ASSUME(B_ABILITY_TRIGGER_CHANCE >= GEN_4);
+        ASSUME(gMovesInfo[MOVE_TACKLE].makesContact);
+        PLAYER(SPECIES_WOBBUFFET) { Gender(MON_MALE); }
+        OPPONENT(SPECIES_CLEFAIRY) { Gender(MON_FEMALE); Ability(ABILITY_CUTE_CHARM); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_TACKLE); }
+        TURN { MOVE(player, MOVE_TACKLE); }
+    } SCENE {
+        ABILITY_POPUP(opponent, ABILITY_CUTE_CHARM);
+        ANIMATION(ANIM_TYPE_STATUS, B_ANIM_STATUS_INFATUATION, player);
+        MESSAGE("Foe Clefairy's Cute Charm infatuated Wobbuffet!");
+        MESSAGE("Wobbuffet is in love with Foe Clefairy!");
+    }
+}

test/battle/ability/effect_spore.c

@@ -0,0 +1,90 @@
+#include "global.h"
+#include "test/battle.h"
+
+SINGLE_BATTLE_TEST("Effect Spore only inflicts status on contact")
+{
+    u32 move;
+
+    PARAMETRIZE { move = MOVE_TACKLE; }
+    PARAMETRIZE { move = MOVE_SWIFT; }
+    GIVEN {
+        ASSUME(gMovesInfo[MOVE_TACKLE].makesContact);
+        ASSUME(!gMovesInfo[MOVE_SWIFT].makesContact);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_BRELOOM) { Ability(ABILITY_EFFECT_SPORE); }
+    } WHEN {
+        TURN { MOVE(player, move, WITH_RNG(RNG_EFFECT_SPORE, 1)); }
+        TURN {}
+    } SCENE {
+        if (gMovesInfo[move].makesContact) {
+            ABILITY_POPUP(opponent, ABILITY_EFFECT_SPORE);
+            ANIMATION(ANIM_TYPE_STATUS, B_ANIM_STATUS_PSN, player);
+            MESSAGE("Wobbuffet was poisoned by Foe Breloom's Effect Spore!");
+            STATUS_ICON(player, poison: TRUE);
+        } else {
+            NONE_OF {
+                ABILITY_POPUP(opponent, ABILITY_EFFECT_SPORE);
+                ANIMATION(ANIM_TYPE_STATUS, B_ANIM_STATUS_PSN, player);
+                MESSAGE("Wobbuffet was poisoned by Foe Breloom's Effect Spore!");
+                STATUS_ICON(player, poison: TRUE);
+            }
+        }
+    }
+}
+
+SINGLE_BATTLE_TEST("Effect Spore causes poison 9% of the time")
+{
+    PASSES_RANDOMLY(9, 100, RNG_EFFECT_SPORE);
+    GIVEN {
+        ASSUME(B_ABILITY_TRIGGER_CHANCE >= GEN_5);
+        ASSUME(gMovesInfo[MOVE_TACKLE].makesContact);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_BRELOOM) { Ability(ABILITY_EFFECT_SPORE); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_TACKLE); }
+        TURN {}
+    } SCENE {
+        ABILITY_POPUP(opponent, ABILITY_EFFECT_SPORE);
+        ANIMATION(ANIM_TYPE_STATUS, B_ANIM_STATUS_PSN, player);
+        MESSAGE("Wobbuffet was poisoned by Foe Breloom's Effect Spore!");
+        STATUS_ICON(player, poison: TRUE);
+    }
+}
+
+SINGLE_BATTLE_TEST("Effect Spore causes paralysis 10% of the time")
+{
+    PASSES_RANDOMLY(10, 100, RNG_EFFECT_SPORE);
+    GIVEN {
+        ASSUME(B_ABILITY_TRIGGER_CHANCE >= GEN_5);
+        ASSUME(gMovesInfo[MOVE_TACKLE].makesContact);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_BRELOOM) { Ability(ABILITY_EFFECT_SPORE); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_TACKLE); }
+        TURN {}
+    } SCENE {
+        ABILITY_POPUP(opponent, ABILITY_EFFECT_SPORE);
+        ANIMATION(ANIM_TYPE_STATUS, B_ANIM_STATUS_PRZ, player);
+        MESSAGE("Foe Breloom's Effect Spore paralyzed Wobbuffet! It may be unable to move!");
+        STATUS_ICON(player, paralysis: TRUE);
+    }
+}
+
+SINGLE_BATTLE_TEST("Effect Spore causes sleep 11% of the time")
+{
+    PASSES_RANDOMLY(11, 100, RNG_EFFECT_SPORE);
+    GIVEN {
+        ASSUME(B_ABILITY_TRIGGER_CHANCE >= GEN_5);
+        ASSUME(gMovesInfo[MOVE_TACKLE].makesContact);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_BRELOOM) { Ability(ABILITY_EFFECT_SPORE); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_TACKLE); }
+        TURN {}
+    } SCENE {
+        ABILITY_POPUP(opponent, ABILITY_EFFECT_SPORE);
+        ANIMATION(ANIM_TYPE_STATUS, B_ANIM_STATUS_SLP, player);
+        MESSAGE("Foe Breloom's Effect Spore made Wobbuffet sleep!");
+        STATUS_ICON(player, sleep: TRUE);
+    }
+}

test/battle/ability/flame_body.c

@@ -29,3 +29,21 @@ SINGLE_BATTLE_TEST("Flame Body inflicts burn on contact")
         }
     }
 }
+
+SINGLE_BATTLE_TEST("Flame Body triggers 30% of the time")
+{
+    PASSES_RANDOMLY(3, 10, RNG_FLAME_BODY);
+    GIVEN {
+        ASSUME(B_ABILITY_TRIGGER_CHANCE >= GEN_4);
+        ASSUME(gMovesInfo[MOVE_TACKLE].makesContact);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_MAGMAR) { Ability(ABILITY_FLAME_BODY); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_TACKLE); }
+    } SCENE {
+        ABILITY_POPUP(opponent, ABILITY_FLAME_BODY);
+        ANIMATION(ANIM_TYPE_STATUS, B_ANIM_STATUS_BRN, player);
+        MESSAGE("Foe Magmar's Flame Body burned Wobbuffet!");
+        STATUS_ICON(player, burn: TRUE);
+    }
+}

test/battle/ability/poison_point.c

@@ -30,3 +30,22 @@ SINGLE_BATTLE_TEST("Poison Point inflicts poison on contact")
         }
     }
 }
+
+SINGLE_BATTLE_TEST("Poison Point triggers 30% of the time")
+{
+    PASSES_RANDOMLY(3, 10, RNG_POISON_POINT);
+    GIVEN {
+        ASSUME(B_ABILITY_TRIGGER_CHANCE >= GEN_4);
+        ASSUME(gMovesInfo[MOVE_TACKLE].makesContact);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_NIDORAN_M) { Ability(ABILITY_POISON_POINT); }
+    } WHEN {
+        TURN { MOVE(player, MOVE_TACKLE); }
+        TURN {}
+    } SCENE {
+        ABILITY_POPUP(opponent, ABILITY_POISON_POINT);
+        ANIMATION(ANIM_TYPE_STATUS, B_ANIM_STATUS_PSN, player);
+        MESSAGE("Wobbuffet was poisoned by Foe Nidoran♂'s Poison Point!");
+        STATUS_ICON(player, poison: TRUE);
+    }
+}