Just copying the ruleset you can find on https://www.speedrun.com/smo?h=100&x=n2y5jwek
In order to get 100% you have to fulfill the following requirements:
Collect all 880 non duplicate moons from every kingdom Buy every souvenir Buy every costume (except for 1.2 DLC) Buy every hat (except for 1.2 DLC) Capture all 52 enemies Fill out the entire music list (82 songs)
(* the 1.2 DLC hats and costumes are marked as "special" in the shop inventory)
This can be verified with a star appearing on your save after completing all of these.
Technically there is the SMO MBM over on the CE board: https://www.speedrun.com/multimarioce?h=Main_Board_Marathon-SMO&x=9d88o76d-wlekvg2l.qyzv27d1
You can now submit runs to the 602 and 1862 leaderboards under the TA filter if you took breaks for sleep and paused the timer! Rules will be more in depth on the category pages on the leaderboard.