From the Super Mario Wiki
Chuckola Bounce is a minigame played in the Winkle Colosseum in Chucklehuck Woods in Mario & Luigi: Superstar Saga during Mario and Luigi's search for the last piece of the Beanstar, which for 500 Coins they can play. The arena is a round room with Chuckoroks around the edge. Mario and Luigi control either side of a Chuckola Board which is used to bounce the Chuckola Rocks that the Chuckoroks shoot at the player back at them. If a brother is hit by the Chuckola Rocks, they will spin around for a few seconds. When the snail resembling Winkle at the bottom left corner reaches the "Time's Up" sign at the bottom right corner, that game is over. Each Chuckorok hit is worth one point. At the end, the player's tally is added up and the total is their score. Occasionally, the Chuckoroks will spit out a Barrier Mushroom. If a brother touches this mushroom, he will be able to touch a Chuckola Rock and hit it back at a Chuckorok without spinning out. As Chuckoroks are hit, they become increasingly smaller, and therefore harder to hit.