The mushroom is a basic power-up in A Koopa's Revenge 2.
In Sackboy's Revenge
Accessible from the first level, the cupcake takes the place of the Shirt from A Koopa's Revenge, restoring Sackboy's shirt if damage was taken and it was lost.
In A Sackboy's Revenge 2
If Sackboy, Orange or  are vulnerable, then the mushroom can be used to give them one extra hit.
When being used, the mushroom will change Koopa's, Goomba's or Shy Guy's appearance to:
- give Sackboy their shirt.
- change Orange back from a Baby Orange.
- give Kirby back their mask.