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

SOS Encounter: Akala Outskirts, Route 8
Super Rod: Route 8 (5%), Akala Outskirts (5%, Only in Ultra Sun & Ultra Moon)
Surf: Route 8 (35%), Akala Outskirts (35%, Only in Ultra Sun & Ultra Moon)
+ 1 more way

Chinchou also appears in

How to get Chinchou 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 Quick Ball or Dive Ball.

Evolution: Chinchou → Lanturn (Level 27).

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