WASD for Me, arrows for Bowser.
Note: I am not the opponent here. If you know anything about Super Mario Bowser fights, you'd know that the player is on the left, whereas in FNF, the player is on the right. Also, the reason I look like the glitch where you're small but have the Fire Flower, that's because only Super Stars and Fire Flowers do anything to me. It's like when you collect a Mushroom but you're already Super Mario.