Break the Ice!
From the Super Mario Wiki
The player uses and , , and to play. The player must press a series of buttons that appear on the top screen for Knuckles to punch through the ice within forty-five seconds. Each time a button is successfully pushed, the buttons on the top screen show up faster. Once a combo of ten is reached, Knuckles will have a rush attack. When this happens, two buttons will appear on the screen. The player will then alternate pressing those two buttons as quickly as possible.
Press the indicated button to punch the ice. Get 10 in a row to perform a rush attack!