Any at all? Because officially the first Wario Land was called Super Mario Land 3. I'd like to see a few things like those floating spiky things that stay in a fixed position. Ramp pieces could be used the way Wario uses them to roll if you can change playable characters because you'd get tired of making stages specifically for Mario.
Would be really cool but I reckon there is a zero chance of that happening. It'd be great if there were more playable characters to choose from in Mario Maker, there probably should be at least Luigi.