Eevee had three evolutions in the original Pokémon games.
Pokémon Red and Blue introduced Vaporeon, Jolteon, and Flareon as Eevee’s three possible evolutions. Each one is associated with a different elemental stone: a Water Stone, Thunder Stone, or Fire Stone. The choice of stone determines which evolutionary form the player receives.
Eevee’s branching evolution system made it unusual among the first-generation Pokémon. Most species followed one fixed evolutionary path, while Eevee offered a choice among three types and three designs.
Later games added five more Eeveelutions: Espeon, Umbreon, Leafeon, Glaceon, and Sylveon. That eventually brought Eevee’s total to eight, which is why modern fans may remember a larger number. Only the first three existed when the original games launched.