Umbreon

Umbreon is a Dark-type Pokémon from the Johto region. It evolves from Eevee after being fed 25 candies and has walked 10 km as a Buddy Pokémon, and evolving it still being Buddy during the nighttime in game.

Trivia

 * Umbreon was a 3rd tier Raid Boss before Halloween 2019.
 * 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.