Bowser leaves due to being too constipated to properly fight.

Darth Vader uses the dark side of the force to turn his skin black, causing Frieza to die of a heart attack.

Sephiroth takes one look at Black Darth Vader and gets an erection so big, that he dies of boiling testicular cancer.

Iron Monger found Black Darth Vaders raw black power to be so much, that he died of bowel inflammation.

Chernabog thought he would survive because he is blackish, but Darth Vader is blacker, causing Chernabog to die.