I have been having an idea of a low% for the game (which is to beat it without using power-ups, kill any enemies (except for boss), using shells against enemies (except for 3rd boss). Time starts and stop the same as any%

Wouldn't the "killing enemies" rule only apply to some kind of "Pacifist" category? Anyway, it would be interesting to see some "challenge" categories, and how the routes would change with the new rules.

Yeah low% is just least amount of items required, so in this case that would mean no powerups. Oof that would be tedious.