Only in Black 2 & White 2
Hidden Grotto: Hidden Grotto
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.
Umbreon in every game · Pokémon Black & White / Black 2 & White 2 interactive map (Unova)