SOS Encounter: Route 10, Route 11, Route 17 + 2 more
Walk: Route 10 (20%), Route 11 (20%), Route 17 (20%) + 2 more
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 Timer Ball, Level Ball or Poké Ball.
Evolution: Ledyba → Ledian (Level 18).
Ledian in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)