A stock item is an item encased within a bubble that allows the player to store food from the Waddle Dee Café or power-ups from Waddle Dee's Item Shop for use at any time. Stock items are used by briefly holding down the button. The player can only hold one stock item at a time and is forced to drop the currently held stock item if another is picked up. Stock items, along with their effects, can be shared in multiplayer.
Carrying certain Stock Items into the Colosseum, or receiving these buffs during the resting area, will make the final score labeled as "Assisted", with the mark of the buff(s) used.