SOS Encounter: Brooklet Hill
Surf: Brooklet Hill (40%)
Walk: Brooklet Hill (20%)
Its base catch rate is 200 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 Net Ball or Dive Ball.
Evolution: Dewpider → Araquanid (Level 22).
Dewpider in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)