My first idea would be itemless%, it would work like how sm3dw itemless% is so temporary power ups like the Star and Giga Bell don't count, also mushrooms since it makes the run just a bit better. My second idea would be a relay, you play any one of the game modes, beat that game mode, then switch to the other, and beat tat game mode. My third idea would be Bowser Jr's. difficult level, if you're going to speedrun BF then you will obviously choose a lot of help, but if there are different category's then there's a reason to change the help level. My last idea would be each character has their own category because nobody would use Mario speedrunning sm3dw, but now there is a reason to use Mario. @Chatcatchase123 suggested coinless and damageless too, so thanks for him to the idea!
I would do these: Mario% No Powerups (Basically itemless but with Mario only) Mario Kart 3D% (beat 3-6) Amiibo categories
These were already meme categories prior to Switch (except amiibo)
I think the most important one for now would be Bowser's Fury amiibo%
How about a category where you get all of the Daisy Cats' Cat Shines as fast as possible? I think this will be the most wholesome meme category for Bowser's Fury.
What if we do a Champions Road% Where you complete Champions Road as fast as possible (Like the Moon Cave category in Super Mario Odyssey)
Would Bowser's Fury 2P make sense? I haven't gotten to mess around with it but I feel there may be some tech possible.
Totally second Bowser's Fury 2P, Bowser Jr can collect coins/shine shards + kill enemies so I think there's a lot of potential there
Full Expedition% Beat every captain toad level as fast as possible. (3d world) You can have 2 versions were one you start from a new file, and another where you start from a file with all of them unlocked, you just have to beat them again
Edit: have 2 different sub versions where you need the one in world crown or you don’t need it
Jumpless would be a challenge run more than anything, and the mods have stated how they really don't want Challenge runs on here. As for Max%, for BF it seems to be super short as you can't get the first Shine, and it's already been proven possible for 3DW.