UBs aren't even that bad
>Nihilego is physically frail and doesn't have the best coverage
>Buzzwole is slow without a scarf and specially frail
>Pheromosa is OHKOd by almost any attack, and usually can't afford to do much more than U-Turn, also lacks coverage
>Xurkitree has sky high SpA and that's it, everything else is subpar, is forced to run a scarf or pray that Z-Hypnosis hits
>Kartana's excellent stat spread is offset by weak moves, a poor offensive typing, and pitiful special defense
>Guzzlord
Celesteela is really the only obnoxious one, its most common set is pretty hard to deal with without a dedicated counter, and even then its versatile movepool and stat spread makes it really hard to predict. And while it's annoying, its far from OP.
