Eeveelution

Eevee's unique trait of evolving into different types can be traced back to a request made by Game Freak CEO, Satoshi Tajiri, to have a Pokémon that evolves into multiple types. Eevee itself was designed as a "blank slate" for varied Evolutions to come. Motofumi Fujiwara designed Eevee, Jolteon, and Flareon. Atsuko Nishida designed all of the other Eeveelutions.

Eevee’s line is & always has been the largest evolutionary line in the Pokedex, with a total of 9 Pokemon. Yes, you heard that correctly - always has been the largest, starting off with 4 Pokemon species in Generation I. This particular line is currently the only evolutionary line with more than 5 species. It is also the only Evolutionary line which can't be fully fit into a specific party. The Eeveelution line has had new members introduced in the most generations (in this case, four generations).

This is the only evolutionary line where none of the members share a type. Like Eevee itself, its evolutions are quite popular in the Pokémon community. Due to their unique abilities capable of gaining advantages in certain battles when multiple different members of the species are used in the player's party as well as adding considerable replay value in the core series, Eeveelutions are highly sought after among collectors when it goes about a full set of all eight evolved forms, sometimes including Eevee to make it complete.