I don't know if it's a bug or not. If we transform Hoopa into unbound form it will sometimes change back to its normal form when we sent it out from pokeball (This bug occurs while I'm playing in my own server). And there is another one that I found out and that is the move "Hyperspace Fury" still remain after it transform back to normal (transform by itself like I mention above). The move should be reverted back to Hyperspace Hole I think and it shouldn't be able to revert itself without the Prison bottle.
I don't know if it's a bug or not. If we transform Hoopa into unbound form it will sometimes change back to its normal form when we sent it out from pokeball (This bug occurs while I'm playing in my own server). And there is another one that I found out and that is the move "Hyperspace Fury" still remain after it transform back to normal (transform by itself like I mention above). The move should be reverted back to Hyperspace Hole I think and it shouldn't be able to revert itself without the Prison bottle.