The Pokémon that your Eevee evolves into is usually randomised in Pokémon GO, but players soon discovered that using specific nicknames would determine whether the pocket monster would become Flareon, Jolteon or Vaporeon.
With Niantic adding 80 new Pokémon that had been originally discovered in the Johto region, that same trick will allow players to evolve Eevee into Umbreon or Espeon. And, it’s as simple as before.
When you have caught an Eevee, select the Pokémon within the list of those that you have captured and tap the pencil icon next to their name. This will let you give the Pokémon a nickname of your choice, for which two specific nicknames can determine whether Eevee will evolve into Umbreon or Espeon.
Those nicknames are Tamao and Sakura, which will unlock Umbreon and Espeon respectively. As with Gen I, these are believed to be one-time use codes which may only be used for the first time that you have Flareon, Jolteon and Vaporeon.