Glitch

Species
Sylveon / Eevee

Dex No.
700

Nature
Timid

Type
Fairy

Held Item
Soothe bell

Pokéball
Love ball with star seal

Favorite Berry
Pecha

G͡l̢̡it̸c͠h̕͢, The Malfunctioning Sylveon.

Glitch is a small shiny Sylveon ♂ with Eevee-like proportions and extra fluffy, light-colored fur.

He caught Pokérus as an Eevee and evolved while still sick with the virus, and his evolution was corrupted.
Sylveon's evolution is typically permanently triggered by a close bond, but Glitch's evolution didn't permanently 'set'.

The side effect of Pokérus made his evolution conditional on his emotional state, negative emotions can cause him to devolve.

When he glitches, he first feels unstable and 'staticky'.
If pushed further, his entire form distorts, pixelising and hue-shifting, and he temporarily de-evolves to a shiny Eevee.

Soothe Bell and other comfort items help keep his form stable.