Toxeon

Dimension A
In Dimension A, toxeon are the poison-type eeveelution and are described as having purple fur that seemed to ooze poison, wispy ears and tail (similar to that of a leafeon), grey eyes, and sharp poisonous spikes circling their neck.

The most prominent example of a toxeon is Acid, one of the few council members of the Forest Clan.

Dimension B
In Dimension B, toxeon is also the name describing the poison-type eeveelution. They have snow-white fur with flecks of purple spotted throughout, long ears with ragged ends, and a thin but powerful tail with a green spike at the end. The tail can be manipulated with ease and is used as a weapon, similarly to that of a scorpion. They also have deep red eye and have a wraith of thin purple poisonous fog surrounding the neck, similarly to that of a gastly's aura.

Pecha berries are deadly to toxeon, as eating one would completely dry their poisonous sacks and stop their heart within a few hours.

An eevee evolves into a toxeon when they are defeated and poisoned in battle, to the point of near death.

Pokédex Entry:
The Dimension B toxeon was actually given a Pokédex entry by FuriousDedenne."'A toxeon uses its long tail like a scorpion, bringing it high above its head to strike its opponent down with the highly poisonous spike on the end. Humans have used toxeon venom for centuries in medicine.'"Currently, this Pokédex entry contradicts the idea that humans have rarely come across any of the custom eeveelutions due to them staying mainly in Eevee Isle. However, an exception may be made in the case of toxeon, as the way an eevee becomes one could allow a fair few to pop up throughout the wild.

Trivia:
 * The toxeon from Dimension A was created by Captain Black Knight.
 * The toxeon from Dimension B was created by FuriousDedenne.