Gastrodon

Like most of its fellow Water-types, Gastrodon has a good movepool and fairly decent stats in general. It also has a great defensive typing that leaves it with only one weakness--Grass-type moves--that can be easily played around with through proper team support. While powerful physical attacks may hurt Gastrodon, its resistances to Rock and Fire and immunity to Electric grant it plenty of opportunities to switch in. Resistance to Stealth Rock and access to Recover make that task of switching in all the more easier in the long run. This, in addition to its decent attacking stats, allow Gastrodon to play a couple of roles effectively. All in all, despite not having a great ability, such as Water Absorb or Marvel Scale, Gastrodon's unique assets allow it to function exceptionally well in UU.