Gift: Iki Town (Only in Sun & Moon), Route 1 (Only in Ultra Sun & Ultra Moon)
You won't find Rowlet in the wild in this game — you get it as a gift.
Looking for Dartrix? It isn't found in the wild in this game — evolve Rowlet (Level 17).
For the look, the best colour match is Nest Ball or Friend Ball.
Evolution: Rowlet → Dartrix (Level 17) → Decidueye (Level 34).
Rowlet in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)