SOS Encounter: Route 8 (15%), Wela Volcano Park (15%, Only in Ultra Sun & Ultra Moon)
Walk: Route 8 (15%, Only in Sun & Moon)
Its base catch rate is 120 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 Level Ball, Repeat Ball or Timer Ball.
Evolution: Fletchling → Fletchinder (Level 17) → Talonflame (Level 35).
Fletchinder in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)