Championships are a multiplayer event that can be unlocked by completing all Qualify tracks in each Career region.
In this optional mode, you:
Race up to 99 other real players
Have a set amount of time to race each track
Have unlimited restarts within that time frame
Earn an overall finish based on your best track times on all tracks
Have a chance to unlock awesome prizes based on your overall finish
Must set times on each track to be eligible for prizes
The goal of this mode is to climb the leaderboard and achieve the highest position possible. To do this you should use all the allowed time on each track. After you win a race replay that same track and you'll automatically be paired against another rider with a slightly faster time than you.
Championships are 3 hours in duration. Once a Championships ends you can claim your prize. You can join a new Championship as soon as your current Championship ends. You can also join multiple different Championships at once. Championships are the best way to earn extra coins.