I'm interested in seeing a All Unlockables/100% Category added to SSL. My run timing started on hitting Enter on the Title Screen, and ended on the last Stage Unlocked Message. If this were to become a Speedrun, I would recommend separating 100% Singleplayer and Co-op to Two Separate Categories, as Unlocking ClownTown would be significantly faster in Coop than Singleplayer, and otherwise making the run require Multiplayer to be viable.
Unlock All Characters would be RNG for Vaporeon, and playing Arcade Mode as the Starting Characters, while Unlocking Clowntown would be either Controlling Two Players at the same time, or grinding 100 Battles. For a Alternative Category (Outside of the Two Suggestions and All Unlocks), I could see All Starters Arcade Mode and All Characters being a Option.