Only in Ultra Sun & Ultra Moon
Super Rod: Route 15 (5%), Hau'oli City (5%), Melemele Sea (5%)
Surf: Melemele Sea (55%), Route 15 (35%), Hau'oli City (5%)
SOS Encounter: Route 15, Melemele Sea
Its base catch rate is 255 out of 255 (higher is easier); the catch rate calculator works out your odds with each ball. For the look, the best colour match is Dive Ball or Heal Ball.
Evolution: Clamperl → Huntail · Gorebyss.
Clamperl in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)