From the Super Mario Wiki
The event is played versus style. Players race around on Topmaniac's Saucer. They must jump over hurdles and earn points. Players can also "leapfrog" over other players. ? Switches also have various effects on the stage, such as items and speed of the rotation. Three points are gained for every Hurdle jumped over. If players fall too far behind, they reappear on the other side of the stage.
In this event, players run on a revolving stage to jump over hurdles and rivals for points.