From WiKirby, your independent source of Kirby knowledge.
An Assist Star is an item which can be collected in Kirby: Triple Deluxe and Kirby: Planet Robobot. It resembles a star-shaped bubble containing a Food item of some sort.
Assist Stars are handed to Kirby (or another character) by Bandana Waddle Dee in specific parts of stages. When collected, it occupies a spot in the lower screen of the Nintendo 3DS system, and can be accessed at any time when the player taps it on that screen. Doing so will activate the Food item inside, restoring Kirby's stamina by a certain amount.
Only one Assist Star can be held at a time. Attempting to collect another will cause it to replace the one previously held, with the replaced star being ejected from Kirby and left to float in the air, where it can be re-collected. An Assist Star will not linger in Kirby's inventory if the game is reset, or a Game Over occurs.
Assist Stars can contain the following items:
Assist stars are also encountered in The Arena and The True Arena.