In the original Pokemon (or season one) Eevee was one of kind Pokemon as it can evolve into one of three Pokemons:
Flareon, the fire pokemon. Wheen Eevee is exposed to the fire stone it evolves to Flareon
Jolteon, the electrical pokemon. Wheen Eevee is exposed to the Thunder stone it evolves to Jolteon
Vaporeon, the electrical pokemon. Wheen Eevee is exposed to the Water stone it evolves to Vaporeon Now if you catch Eevee in poekmon go and you want to evolve him, which on will you get ? There is a trick to pick which one Eevee will evolve to:- For Flareon rename Eevee to Pyro before you evolve him. For Jolteon rename Eevee to Sparky before you evolve him. For Vaporeon rename Eevee to Rainer before you evolve him.