From the Super Mario Wiki
The player moves the character along during the minigame. Players must avoid obstacles such as fire, dodge Bullet Bills shooting out of a cannon. Then the player will face a burned portion of the road. To pass, the player will need to call the party using the command "Mario Party" with the microphone, and order them to cool the road. The player will then face more obstacles before finding a locked door. Using the same previous method, the allies will knock the door down. Finally the player reaches the finish line.
Microphone: Order commands for the CPU allies to cool down a road with a pump, and to punch a door to knock it down.