I've been having second thoughts on whether 100% should be an official category for this game (I am not one of the moderators, but just roll with me on this). The rules for 100% should be all rings collected in the individual levels, but, I have discovered a bug that not very many people are familiar with: Let's say that there are three rings in a row in a certain area of the map. You try to collect them by spindashing towards them, but the ring counter says you collected two rings instead of three. I have no idea why this happens, but I'm sure it's got something to do with the development of the game itself. I am still trying to go through the first stage of the game to see how many rings are in it. But, can 100% be a category for this game? The answer is yeah, kind of. You need to be very specific with your movements. There are no special items that I am aware of that you can collect within the game, so I think the rules to 100% should be collect all rings within the individual levels.
I would think 100% is to start the game completely blank and then get every cheat and character.