Eevee can evolve into eight different Pokémon in the Pokémon video-game series.
The first three evolutions appeared with Eevee in Pokémon Red and Blue: Vaporeon, Jolteon, and Flareon. They are produced with Water, Thunder, and Fire Stones, respectively, giving Eevee access to three different elemental forms.
Later games added Espeon and Umbreon, which depend on friendship and time of day, followed by Leafeon and Glaceon, whose evolution methods have varied between games. Sylveon, the Fairy-type evolution, became the eighth Eeveelution when it debuted in Pokémon X and Y.
Eevee is called the Evolution Pokémon because its unstable genetic code allows several evolutionary outcomes. The term “Eeveelution” is a fan and official-community shorthand for these forms. Pikachu is not one of them: although both are popular mascot Pokémon, Pikachu evolves into Raichu rather than branching into multiple species.