I really like this mod! It's neat to have Whomp King as a playable character, but I have a problem, which is is something that I don't like: the textures. The textures don't really match with the rest of the character, and could surely be improved. Besides that, great work!
Also make it over Roy or some heavy Koopaling? I was looking for mods to replace them all :3 No need to do it tho, I can see it being difficult, although I don't have experience in modding MK8 at all.
I never thought I'd see the Whomp King in a kart. Coolio.
I think the texture for the body is a bit low-res (might just be the lack of baked on shadows to imply the eyebrows/facial features, because without it he just looks like a slab). I'll hold off on rating for right now.