It's similar to some existing Mortasheen monsters, but this was an idea I had for a pokemon whose whole theme would be "grossness." There aren't a lot of pokemon canonically reviled by humans, yet in the real world we have a lot of animals people find ugly and creepy.
I figured this little guy would be like a big ball of warts, filled with rotting slime and bacteria, and like the folkloric Squonk, hates being seen as well as the sight of its own face. All other pokemon and most humans avoid it like the plague :(