While most Pokemon have evolutions that are straightforward, Eevee's fate can be a little more random after evolution. However, there's an easy way for players of "Pokemon GO" to evolve their Eevee into the form they want.
When "Pokemon GO" was released, Eevee had only three evolutions: Vaporeon (water type), Flareon (fire type), and Jolteon (electric type). For players who didn't know the evolution technique for Eevee, they mostly got random results. However, because of several leaks posted online, a lot of people were able to apply the renaming technique which would yield the desired evolution for the Pokemon.
To evolve Eevee into Vaporeon, the player must first rename it to "Rainer." On the other hand, the player must rename it to "Pyro" for Flareon, and "Sparky" for Jolteon. The player must also remember to capitalize the first letter of the name as this may affect the result. Once the changes have been made, Eevee will be ready to transform into the player's desired evolution.
The recent update in February added more than 80 Pokemon to the Pokedex, including two new evolutions for Eevee namely, Espeon (psychic type) and Umbreon (dark type). The renaming technique still stands for these new evolutions, such as "Sakura" for Espeon and "Tamao" for Umbreon. However, it does not end there. There is another step in evolving Eevee into these two.
The trick is to walk 10 kilometers with Eevee selected as the Pokemon Buddy and acquire two candies.
The names Rainer, Pyro, and Sparky were the names of the Eevee brothers whom Ash and his group met in the Pokemon TV series. Sakura and Tamao also appeared later on in the anime series.
According to IGN, evolving Eevee into these Gen 2 evolutions does not have to be done at specific hours of the day. Although players had to evolve Eevee into Espeon during the day and into Umbreon during the night in "Pokemon Silver" and "Pokemon Gold," it does not actually work the same way for "Pokemon GO." Players can evolve their Eevee anytime of the day so long as the necessary steps have been taken.
Other known evolutions for Eevee include Sylveon (fairy type), Glaceon (ice type), and Leafeon (grass type). These have yet to become available in "Pokemon GO."
