The entire shame is a battle between Super Eviler Bowser and Mario. Super Eviler Bowser gets all sorts of cool powers, while Mario occasionally finds a Fire Flower and shoots fireballs. When the player wins the shame (usually in about one minute, due to how powerful Super Eviler Bowser is), Mario is unlocked as a playable character. He always gets the snot beaten out of him by Super Eviler Bowser when played, so it is not fun to play as him.
Bowser gets pissed, so he turns into Eviler Bowser. Mario moons him, so Eviler Bowser turns into the all-powerful Super Eviler Bowser. This gives the player nearly limitless ways to kill Mario. The shame takes place in Mushroom Kingdom, so the player gets to crush everything while chasing Mario.
When the player wins, Mario is unlocked. Mario mode usually lasts about three seconds until Mario is killed.
Super Eviler Bowser's Shame was incredibly popular, as people like pretending they are a god. This angered Chuck Norris, which in turn caused 3,563,641 deaths. But Marx brought them all back to life because he is nice. This shame is now one of the most popular on the Shamecube. Super Eviler Bowser's Shame 2 was going to be released on the Nintendo Wii, but it was cancelled because there is nothing they could add that you can't already do in this shame.