Eevee is a highly popular Pokémon in Pokémon GO and the wider Pokémon franchise. Unlike other Pokémon, Eevee can evolve into one of eight different evolutions: Jolteon, Vaporeon, Flareon, Sylveon, Espeon, Umbreon, Leafeon, or Glaceon. Each of these evolutions transforms from a Normal-type to an Electric, Water, Fire, Fairy, Psychic, Dark, Grass, or Ice-type, respectively.
Eevees are often found wandering the world in Pokémon GO, making them easy to catch. However, naturally evolving every Eevee would make collecting the eight Eevee evolutions a rather difficult task. Luckily, there is a well-known trick to make sure your Eevee evolves as you desire.
Once you get your hands on an Eevee, their nicknames are the key to evolving them into your desired evolution. Like other Pokémon games, you can give them a nickname when you catch a new Pokémon, rather than just calling them by their Pokémon name. The same holds true for Pokémon GO. While nicknames typically change nothing about a Pokémon, if you give your Eevee one of eight unique nicknames, Eevee will evolve into the associated evolution.
If you want to nickname your Pokémon, click on the Eevee of your choice and click on the pen icon next to their name. From there, you can input your Pokémon’s new name. This trick will allow you to collect all eight Eevee evolutions, but the nickname trick will only work once; any other versions of the same evolution must be collected naturally.
When the Eevee nickname trick no longer works, but you still want to evolve your Eevee into a specific evolution, keep in mind the mechanical requirements. All eight evolutions occur based on either RNG or specific player actions.
No matter what you do, your Eevee has a 33% chance of turning into either Vaporeon or Flareon. Jolteon has similar odds but is only added to the pool of evolution outcomes after you feed your Eevee 25 Candies. These three evolutions are highly likely due to their position as the original three evolution outcomes.
Espeon and Umbreon ask you to walk 6.2 miles/10 km to unlock them as possible evolutions, but you must schedule the evolution time. Espeon evolves during the day, while Umbreon evolves at night in Pokémon GO, meaning they will never be evolution outcomes for the same Eevee. Leafeon and Glaceon are dependent on Mossy Lures and Glacial Lures, respectively. Insert one of the two into a PokéStop and evolve your Pokémon nearby to unlock the associated type.
Lastly, Sylveon can only evolve if you have 70 Hearts with the Eevee of your choice, which you can earn by making them your buddy Pokémon. This technique guarantees a Sylveon, as its icon replaces the question mark on the evolve button. While it may take some time if you want to be 100% sure what your Eevee will evolve into in Pokémon GO without nicknames, evolve them into a Sylveon.