Eevee evolves into the greatest number of different Pokémon species.
Eevee is a Normal-type Pokémon introduced in Pokémon Red and Blue. Its unstable genetic code allows it to evolve into multiple forms, collectively nicknamed Eeveelutions. The first three were Vaporeon, Jolteon, and Flareon, each produced using a different elemental evolution stone.
Later games added Espeon, Umbreon, Leafeon, Glaceon, and Sylveon. These evolutions use different conditions, including friendship, time of day, locations, moves, and evolutionary stones. Because the methods vary, Eevee is both a collecting challenge and a showcase for how Pokémon evolution mechanics developed across generations.
Eevee is sometimes confused with Tyrogue, which can evolve into Hitmonlee, Hitmonchan, or Hitmontop depending on its statistics. That is a branching evolution line, but it has fewer outcomes. Eevee’s broad range of forms and types has made it one of the franchise’s most popular species, alongside Pikachu, and it received its own Nintendo Switch title, Pokémon: Let’s Go, Eevee!.