With the arrival of Gen 2 monsters in "Pokemon GO," Eevee can now evolve into Espeon and Umbreon. In other "Pokemon" games, Eevee will evolve into either of the two depending on the time of day.
Espeon will be obtained upon evolving the creature from 4 a.m. and 8 p.m. and an Umbreon between 8 p.m. and 4 a.m. In the mobile app, there are two ways to get either one: the naming trick and the buddy system trick.
According to The Inquisitr, the "Pokemon GO" Eevee naming trick is like that for Vaporeon, Flareon, and Jolteon. To get the Gen 1 Eeveelution that the players want, they must name their monster Pyro for Flareon, Rainer for Vaporeon and Sparky for Jolteon. It is the same for Espeon and Umbreon: the Eevee must be named Sakura or Tamao respectively.
However, this trick can only be used once. When a player has already used both names on their Eevee, they would not be able to use them again to get the "Pokemon GO" Gen 2 evolution. Fortunately, there is another trick that can be used again and again to get an Umbreon or Espeon.
The "Pokemon GO" Eeveelution buddy system trick borrows some mechanics from the original "Pokemon" games wherein Eevee has to be evolved at a certain time of the day to get the preferred evolution while making sure that the monster has a certain friendship level with the trainer.
In "Pokemon GO," however, players have to appoint Eevee as their Buddy Pokemon and walk 10km with it, according to Pokemon GO Informer. While doing so, the players will receive two candies, which they can use to evolve the Eevee.
The same Eevee that was made the Buddy Pokemon should be the one to evolve. Otherwise this trick will not be effective. Based on the local time of the player, which is displayed in the app, the Eevee will evolve into Espeon or Umbreon.
As mentioned above, this "Pokemon GO" Eevee evolution trick can be done again and again. This is a great way of getting an Umbreon or Espeon every time the player wishes to.