SOS Encounter: Route 17 (15%, Only in Sun & Moon & Ultra Sun), Route 10, Mount Hokulani + 1 more
Walk: Mount Hokulani (70%), Route 10 (30%), Route 17 (30%) + 1 more
Surf: Route 10 (80%), Poni Plains (70%)
Its base catch rate is 90 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 Nest Ball, Safari Ball or Level Ball.
Evolution: Spearow → Fearow (Level 20).
Fearow in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)