PvP -Champions Meeting
Champions Meeting is a monthly 3v3v3 PvP tournament where every race takes place on the same track, so you can make highly specialized umas. The rewards are very good:

Use this site to simulate the specific track the race will be run on (see more in Analyzing Tracks)
Brackets

There are two different brackets in Champions Meeting, the Graded League and the Open League. In the Graded League (right, red button), you can use any uma. In the Open League (left, green button), you can only use umas that are B or worse. After the tournament starts, you can’t change your decision.
The rewards in the Graded League are much better than the rewards in the Open League. For example, coming in 3rd during the Grade finals is pretty much as rewarding as coming in 1st during the Open finals. If you can make A rank umas, the Graded League is likely the better choice.
Rounds

The first two rounds last for two days each, and you can enter up to 4 times per day, with each entry being 5 races. So, in each of the first two rounds, you have 8 opportunities to get a good score. Your best score is all that matters, so don’t be scared to keep using entries after advancing to Group A.
If you for some reason want to avoid getting into Group A, e.g. you think you wouldn’t be able to get 2 wins in Round 2 Group A, you can retire the run after getting 2 wins. In Round 2, you might as well keep going, since 3rd in Group A Finals is almost as good as 1st in Group B Finals.
The Final Round is only a single race. After Round 2, there will be a 12 hour period where you can register the umas you’ll use in the Final Round. If you don’t register any, it will use the umas you used for your last entry. Then, there will be a matching period where the game chooses who your opponents will be. After that, you can see the results.
You will race against other players, but you may not race them at the same time. People have raced against my umas in CM while I was asleep before. I’m not sure if it’s always asynchronous like that or if it only sometimes is (e.g. during long queue times).