It’s one of the franchise’s key mascots and one of the original 151 Pokémon, yet we haven’t seen Eevee receive a new ‘Eeveelution’ for a decade. Fans are still guessing as to why exactly this remains the case.
A little bit of history for those not informed. Eevee was incredibly unique back in Pokémon Red, Blue, Green, and Yellow. Although many of its fellow 151 could evolve, this ‘Evolution Pokémon’ had three distinctly different secondary forms based on which type of stone you paired it with. The roster of Flareon, Vaporeon, and Jolteon was expanded by two for Gen II: The Psychic-type Espeon and Umbreon, who represented the debuting Dark-type. These forms required high friendship during the day or night respectively.