>>26719093Not really. If you were to Synchro with a Greninja of your own, the design would obviously change. This particular Greninja is associated with Ash because it's his, likewise the transformation would look different for another trainers.
That's like saying every other Saiyan in DBZ should be able to go Super Saiyan because that transformation is associated with Goku.
Also assuming it's in other games, the transformation would likely be available for other Pokemon, there's no reason why Greninja alone has to be the only Pokemon capable of Synchro.
