Sans

Sans is a skeleton hailing from the faraway dimension of Undertale. He is very humerus.

Skeleton of Revenge
Sans is a skeleton that just up and appeared one day in the monster world, nobody knowing where he came from or who he was there.

A boy would later appear and make a few shenanigans with the timeline while Sans watched him or something.

Season 4
However, Sans managed to build his machine and and returned the the place he once came from.

Despite nobody knowing or recognizing him, Sans claims to be very familiar with The Final Rumble and it's people. ESPECIALLY a certain agent. Now, Sans joins TFR mostly for fun since he isn't much fond of wrestling, or at least, that's what he wants people to believe.

Episode 3
Now, tired of being a lazy bones, Sans is concerned about someone as strong as the boy showing up, and decided to join a group of investigators to find out more.

However, it didn't turn out very well, as this body of his is pure bones.

Season 5
Along with 60 others, he went to a special conference about wrestling after the Kojima Incident, and was trapped in the in Universe 2K20 by La Parka.

Episode 1
He was selected for the non-candidate where the first 10 eliminated  and the winner and highest killer wins .