I know not many people run this game and especially the all worlds category (full game category) but wouldn't a 100% category be good. Rules are simple: complete all levels (1-1 through 20-8), break and collect all clover blocks, kill all enemies, collect all gold pots and coins. Another idea is the Perfect% category. Basically beating the game without losing a life (not "don't get a game over", "don't lose a life/don't take any damage). I hope these are helpful ideas.

Those categories are potentially possible imho, yea.
However, there haven't been any All Worlds runs at all (not even of any%) so I'm reluctant to add more categories in that regard, but if there was a run I'd probably add the category.