Three lategame categories that would make sense for the leaderboard are All Silvers, All Golds, and 100%. Obviously, these won't get a lot of runs, but they are categories to look into.

All Silvers: Pretty straightforward. It would require getting all silver keys on Wii version and all silver stars on Switch.

All Golds: Not as straightforward. All gold keys on Wii, but I'm unsure what this would be on Switch. Gold keys/stars don't appear to be present here, so this is uncertain.

100%: Pretty straightforward. All gold keys, photo spots, and treasure chests on Wii. You'd get all silver stars, photo spots, treasure chests, and animal photos on Switch, and maybe max level, but I'm not sure. (You would also have to get '5's instead of '4's where applicable and get all fish in Scuba Diving.)

As I said before, these are categories that don't need to be added any time soon, but perhaps keep them in the back of your mind just in case.

These are some great ideas that could definitely become future categories! As they would be very long runs I don't think I would run them myself but could set up a leaderboard should anyone decide to do a run of them. Thank you for your ideas.