Only in Ultra Moon
SOS Encounter: Poni Breaker Coast
Surf: Poni Breaker Coast (20%)
Its base catch rate is 55 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 Dream Ball, Heal Ball or Master Ball.
Evolution: Skrelp → Dragalge (Level 48).
Dragalge in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)