diff --git a/src/battle-scene.ts b/src/battle-scene.ts
index 0efc4dc8d..30c6c5603 100644
--- a/src/battle-scene.ts
+++ b/src/battle-scene.ts
@@ -936,6 +936,8 @@ export default class BattleScene extends SceneBase {
 			case Species.TATSUGIRI:
 			case Species.PALDEA_TAUROS:
 				return Utils.randSeedInt(species.forms.length);
+			case Species.MINIOR:
+				return Utils.randSeedInt(6);
 			case Species.MEOWSTIC:
 			case Species.INDEEDEE:
 			case Species.BASCULEGION:
diff --git a/src/data/ability.ts b/src/data/ability.ts
index a0645d4af..7cb03d7e7 100644
--- a/src/data/ability.ts
+++ b/src/data/ability.ts
@@ -2536,9 +2536,9 @@ export function initAbilities() {
       .attr(PostDefendContactDamageAbAttr, 8)
       .bypassFaint(),
     new Ability(Abilities.ZEN_MODE, "Zen Mode", "Changes the Pokémon's shape when HP is half or less.", 5)
-      .attr(PostBattleInitFormChangeAbAttr, p => p.getHpRatio() >= 0.5 ? 0 : 1)
-      .attr(PostSummonFormChangeAbAttr, p => p.getHpRatio() >= 0.5 ? 0 : 1)
-      .attr(PostTurnFormChangeAbAttr, p => p.getHpRatio() >= 0.5 ? 0 : 1)
+      .attr(PostBattleInitFormChangeAbAttr, p => p.getHpRatio() <= 0.5 ? 1 : 0)
+      .attr(PostSummonFormChangeAbAttr, p => p.getHpRatio() <= 0.5 ? 1 : 0)
+      .attr(PostTurnFormChangeAbAttr, p => p.getHpRatio() <= 0.5 ? 1 : 0)
       .attr(UncopiableAbilityAbAttr)
       .attr(UnswappableAbilityAbAttr)
       .attr(UnsuppressableAbilityAbAttr),
@@ -2616,7 +2616,10 @@ export function initAbilities() {
     new Ability(Abilities.WATER_COMPACTION, "Water Compaction", "Boosts the Pokémon's Defense stat sharply when hit by a Water-type move.", 7)
       .attr(PostDefendStatChangeAbAttr, (target, user, move) => move.type === Type.WATER, BattleStat.DEF, 2),
     new Ability(Abilities.MERCILESS, "Merciless (N)", "The Pokémon's attacks become critical hits if the target is poisoned.", 7),
-    new Ability(Abilities.SHIELDS_DOWN, "Shields Down (N)", "When its HP becomes half or less, the Pokémon's shell breaks and it becomes aggressive.", 7)
+    new Ability(Abilities.SHIELDS_DOWN, "Shields Down (P)", "When its HP becomes half or less, the Pokémon's shell breaks and it becomes aggressive.", 7)
+      .attr(PostBattleInitFormChangeAbAttr, p => p.formIndex % 7 + (p.getHpRatio() <= 0.5 ? 7 : 0))
+      .attr(PostSummonFormChangeAbAttr, p => p.formIndex % 7 + (p.getHpRatio() <= 0.5 ? 7 : 0))
+      .attr(PostTurnFormChangeAbAttr, p => p.formIndex % 7 + (p.getHpRatio() <= 0.5 ? 7 : 0))
       .attr(UncopiableAbilityAbAttr)
       .attr(UnswappableAbilityAbAttr)
       .attr(UnsuppressableAbilityAbAttr),
diff --git a/src/data/pokemon-forms.ts b/src/data/pokemon-forms.ts
index e5bcf25a4..2d2d491bf 100644
--- a/src/data/pokemon-forms.ts
+++ b/src/data/pokemon-forms.ts
@@ -549,6 +549,22 @@ export const pokemonFormChanges: PokemonFormChanges = {
     new SpeciesFormChange(Species.WISHIWASHI, '', 'school', new SpeciesFormChangeManualTrigger(), true),
     new SpeciesFormChange(Species.WISHIWASHI, 'school', '', new SpeciesFormChangeManualTrigger(), true)
   ],
+  [Species.MINIOR]: [
+    new SpeciesFormChange(Species.MINIOR, 'red-meteor', 'red', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'red', 'red-meteor', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'orange-meteor', 'orange', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'orange', 'orange-meteor', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'yellow-meteor', 'yellow', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'yellow', 'yellow-meteor', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'green-meteor', 'green', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'green', 'green-meteor', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'blue-meteor', 'blue', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'blue', 'blue-meteor', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'indigo-meteor', 'indigo', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'indigo', 'indigo-meteor', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'violet-meteor', 'violet', new SpeciesFormChangeManualTrigger(), true),
+    new SpeciesFormChange(Species.MINIOR, 'violet', 'violet-meteor', new SpeciesFormChangeManualTrigger(), true)
+  ],
   [Species.NECROZMA]: [
     new SpeciesFormChange(Species.NECROZMA, '', 'dawn-wings', new SpeciesFormChangeItemTrigger(FormChangeItem.N_LUNARIZER)),
     new SpeciesFormChange(Species.NECROZMA, '', 'dusk-mane', new SpeciesFormChangeItemTrigger(FormChangeItem.N_SOLARIZER))
diff --git a/src/field/arena.ts b/src/field/arena.ts
index 11677dc49..a3ba8cb69 100644
--- a/src/field/arena.ts
+++ b/src/field/arena.ts
@@ -166,6 +166,20 @@ export class Arena {
             return 2;
         }
         break;
+      case Species.ROTOM:
+        switch (this.biomeType) {
+          case Biome.VOLCANO:
+            return 1;
+          case Biome.SEA:
+            return 2;
+          case Biome.ICE_CAVE:
+            return 3;
+          case Biome.MOUNTAIN:
+            return 4;
+          case Biome.TALL_GRASS:
+            return 5;
+        }
+        break;
       case Species.SCATTERBUG:
       case Species.SPEWPA:
       case Species.VIVILLON: