>>43761231I'm gonna say Uber prison.
The gap between Uber and OU is wider than the gap between OU and UU.
So most mons in UUBL are at least decent in OU, albeit not good enough to be mainstream picks. Ubers are more likely to end up like Zamazenta or base Deoxys.
That is, assuming the mon actually deserves to be banned. UU has a tendency to go overboard with banning offensive threats.