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

SOS Encounter: Hau’oli Cemetery, Memorial Hill
Walk: Hau’oli Cemetery (50%), Memorial Hill (50%)
Gift: Poké Pelago (Only in Sun & Moon)
+ 1 more way

Gastly also appears in

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

Its base catch rate is 190 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, Dusk Ball or Master Ball.

Evolution: Gastly → Haunter (Level 25) → Gengar (Trade).

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