Umbreon

Umbreon is a Dark-type Pokémon from Johto region. It evolves from Eevee when fed 25 candies.

Pokédex description
Moonlight Pokémon

''Umbreon evolved as a result of exposure to the moon's waves. It hides silently in darkness and waits for its foes to make a move. The rings on its body glow when it leaps to attack.''

Evolution family
Umbreon is the part of a split evolution family.

Trivia

 * There is a continuation of an easter egg that refers to the names of the Eevee Brothers, despite the fact that Tamao wasn't member of Eevee Brother, naming Eevee with her name will result in a Umbreon when it is evolved.
 * Works only once per account and even if Eevee was already evolved into Umbreon not using this method.
 * Walking an Eevee Buddy 10 km or more, and evolving it will cause it to become an Umbreon during the night.
 * Along with Espeon, Umbreon is the only Pokémon in the game that to evolve into it there's no evolution item required but the evolution is the only way to acquire this Pokémon.