lostcarnival has Sans and Papyrus (I'm Sans obviously) and the premise is a world travelling carnival, so performances are definitely an aspect! Mettaton could have the opportunity to perform for the whole multiverse! Which I'm sure would be adequately ego inflating for him.

We've thought that it would be an excellent game for him for a while, so you should def check it out. Papyrus would be extremely excited.

There are transformation aspects too (growing things like claws, horns, tails or many other things) but what you take on is very flexible to your tastes and the minimum of what's required is quite low.

Also Sans is chief of security here so you know its a classy establishment.