SOS Encounter: Route 4 (15%), Route 6 (15%)
Its base catch rate is 45 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 Moon Ball, Ultra Ball or Luxury Ball.
Evolution: Eevee → Vaporeon (Water Stone) · Jolteon (Thunder Stone) · Flareon (Fire Stone) · Espeon · Umbreon · Leafeon · Glaceon · Sylveon.
Umbreon in every game · Pokémon Sun, Moon, Ultra Sun & Ultra Moon interactive map (Alola)