Its Poke-body will probably just be called "plate change" or something, and it's type will be what ever energy you attatch to him.
Either that or there will be plate tools for each type, but they won't just be for him, they'll do something good if they're attatched to any pokemon of that type... just like in the game. I hope they keep him really rare, or you're only allowed 1 in a deck... they spoil legends by making them so common, how many Rayquazzas have been released? definatly more than any Rattata!