Jolteon

Eevee, art by Ken Sugimori. Not all Eeveelutions are pointless - this one is uber-pointy!

Jolteon is an official Electric-type Pokémon introduced in Generation I. It is #135 in the National PokéDex.

It evolves from Eevee via use of a Thunderstone.

.... And it's essentially what happens when an Eevee goes Super-Saiyan.

For more information on Jolteon, see its Bulbapedia entry.

Evolutionary Data:
Eevee → Thunderstone → Jolteon