You have to understand that you don't get many opportunities to place full size images for Wii U themes. the surfaces you can work with are rather small. you probably could have some boobs or dicks tesselate on the floor of the wara wara plaza, but you're not gonna be able to get much more out of it than that, unless you go above and beyond and say replace the 3D modeled buttons that float by in the background with 3D modeled inappropriateness, though I'm not sure if there are file size limits in that kind of stuff, I would think there probably would be, but can't say for sure.