Wickey Wouse is not surprisingly fatter than his original state
Wickey Wouse is an unordinary creature that fused with Wario and Mickey Mouse when he put him in the Wa-Machine. Unfortunately, the Wa-Machine malfunctioned and created a duplicate of them both and fused them together, of now what we call, Wickey Wouse.
Wickey Wouse doesn't do much in the UnWorld but he does stroll around somewhere. He's like Slender Man because you never know where he's going to be. He could be behind a tree, or behind your computer. He gets pissed when he sees people scared of him so he punches them.
We don't know what a Wouse is, but it is probably a genetically modified mouse. If it was Wa-ified, it would be called a WaMouse.