From 2eebf29d92b9e5b66a8ea540c812ed67c9dda8bb Mon Sep 17 00:00:00 2001
From: Kevin Lau <ascriptmaster@gmail.com>
Date: Sat, 21 Mar 2015 19:05:42 -0700
Subject: [PATCH] Generation 4: Fix Transform's interaction with item-based
 forme changes

Causes Dittos transforming into Giratina-O without Griseous Orb to revert
to Giratina-A in Generation 4, etc.
---
 battle-engine.js | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/battle-engine.js b/battle-engine.js
index c2191fc3a5..c91309d76e 100644
--- a/battle-engine.js
+++ b/battle-engine.js
@@ -367,6 +367,30 @@ BattlePokemon = (function () {
 		}
 		if (init) return;
 
+		// Change formes based on held items (for Transform)
+		// Only ever relevant in Generation 4 since Generation 3 didn't have item-based forme changes
+		if (this.battle.gen === 4) {
+			if (this.template.num === 487) {
+				// Giratina formes
+				if (this.template.species === 'Giratina' && this.item === 'griseousorb') {
+					this.formeChange('Giratina-Origin');
+					this.battle.add('-formechange', this, 'Giratina-Origin');
+				} else if (this.template.species === 'Giratina-Origin' && this.item !== 'griseousorb') {
+					this.formeChange('Giratina');
+					this.battle.add('-formechange', this, 'Giratina');
+				}
+			}
+			if (this.template.num === 493) {
+				// Arceus formes
+				var item = Tools.getItem(this.item);
+				var targetForme = (item && item.onPlate ? 'Arceus-' + item.onPlate : 'Arceus');
+				if (this.template.species !== targetForme) {
+					this.formeChange(targetForme);
+					this.battle.add('-formechange', this, targetForme);
+				}
+			}
+		}
+
 		if (this.runImmunity('trapped')) this.battle.runEvent('MaybeTrapPokemon', this);
 		// Disable the faculty to cancel switches if a foe may have a trapping ability
 		for (var i = 0; i < this.battle.sides.length; ++i) {