Shadoo

Shadoo is the boss of the Flopside Pit of 100 Trials. While he was created by the Ancients, he works for his "own cursed powers". When the four heroes make it to Room 100, he tries to beat them and take their place by turning into each hero and copying their moves.

He'll first turn into an entirely black form of Luigi, then Bowser, Peach, and finally Mario. Each form has 100 HP and an attack of 10, in Bowser's case and when Mario uses his hammer, 20. If the heroes don't fight back smartly (such as neglecting to use Barry or even Peach's umbrella to deflect damage) the fight can be lost very easily and all progress in the Pit will be lost.

Upon defeat 8 catch cards appear: one of each of the heroes and their dark forms.