Defeat Bomb Flapper!
From the Super Mario Wiki
Defeat Bomb Flapper! is a minigame in Cubyrinth in the Nintendo DS version of Mario & Sonic at the Olympic Winter Games. The player plays as Waluigi in this minigame. The player moves with the control pad and picks up Bob-ombs with the button. The player must pick up black Bob-ombs dropped by the Bomb Flapper and throw them back at it several times within forty-five seconds. The Bomb flapper will occasionally drop green Bob-ombs, which chase the player. The bombs will turn red and explode within a certain amount of time. If a Bob-omb explodes on Waluigi, he will be stunned for a few seconds, costing the player valuable time.
Throw back Bob-ombs to reduce Bomb Flapper's HP to 0! Green Bob-ombs will chase you!