Where did you hear this?
In addition to what ORAS said above me, Hoopa Unbound itself is not in XY code either. I've tried trading it over myself and it said unable to trade or something like that, and when I tried trading Normal Hoopa, it traded just fine.
As many others said, I really hope Hoopa gets an event in the U.S. Yeah, of course Japan (as usual) gets all the goods. Maybe I'll consider moving to Japan. -_-
I do have issues with how Palkia was involved... it created space and it seems to have the ability to travel through dimensions (same with Dialga and Giratina), yet it and it's trio members were somehow captured by Hoopa...not that being captured by some small pocket sized balls is any better...