Smash games generally don't have CEs because the main and secondary modes are good enough to be on one board (Extras category being an exception for WoL and SSE). Anything outside of the box and other ideas people share usually are too arbitrary to be on a proper leaderboard. If you wish to run random categories you create yourself, nothing is stopping you or anyone else. If others are interested, they could make a spreadsheet for categories, we have a few members of the brawl community who decided to do that.