I finally fulfilled my dream of fighting Super Dimentio at level 1 and this fight was actually pretty hard. I won with Peach and Carrie (Peach can block in midair whilst riding Carrie) and luring the boss into the corner then just jump on his head whilst blocking and although it'd be possible to get hit if a projectile hits you in the split second after you land a hit (because this disables the block) I managed to win doing that, but if I hadn't pulled that off it would've been a very hard fight.