Where to find Sharpedo in Sun, Moon, Ultra Sun & Ultra Moon

SOS Encounter: Poni Breaker Coast (30%), Ancient Poni Path (30%, Only in Ultra Sun & Ultra Moon)
Super Rod: Poni Breaker Coast (1%, Only in Sun & Moon)
Surf: Poni Breaker Coast (10%, Only in Sun & Moon)

Sharpedo also appears in

How to get Sharpedo in Sun, Moon, Ultra Sun & Ultra Moon

Its base catch rate is 60 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 Quick Ball, Lure Ball or Moon Ball.

Evolution: Carvanha → Sharpedo (Level 30).

Sharpedo in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)