Super Eevee

Super Eevee is a special type of Eevee who's DNA structure was mysteriously modified.

Professor Oak was the first to encounter it, "finding it outside his doorstep". The Eevee would then randomly switch between Eevee and Vaporeon, prompting Oak to investigate the phenomenon.

What he found was a exotic DNA structure, one which gave Eevee the ability to switch forms, and potentially generate new ones through experience. Oak created a device called the Tetra Element to give stability to Eevee's forms.

Gold first encounters Eevee in Aurum Creek, who leads him back to Oak's lab. They battle together against Team Rocket, which causes Eevee to generate a new evolution; Jolteon.

Eevee is also unique in that it can create Viruses. The only thing known to be able to kill Hypervisors.