Spiritomb

Spiritomb's typing makes it one of the few Pokemon to have no weaknesses. Combined with its remarkable defensive stats and useful immunities to Fighting-, Normal-, and Psychic-type moves, Spiritomb makes a great defensive Pokemon. However, Spiritomb has a lacking movepool in terms of both offense and support, and has no reliable recovery outside of Rest and Pain Split. The only useful support moves it has access to are Will-O-Wisp, Toxic, and Hypnosis, and most of Spiritomb's attacking moves are either Ghost- or Dark-type. However, Spiritomb does have access to useful moves such as Sucker Punch, Shadow Sneak, and Pursuit, coupled with above average offensive stats, making it one of the best checks to Psychic- and Ghost-type Pokemon in the tier. It also has access to Calm Mind to boost its stats even further. All this, plus having access to Pressure and Infiltrator, makes Spiritomb a great defensive and offensive threat in the UU tier, despite its minor flaws.