The Tournaments of Champions

The Tournament of Champions is an annual event which features 15 of the best players from the previous year's shows. The qualification rules are as follows:

Any contestant who wins 5 games becomes an undefeated champion and automatically qualifies for the ToC. Starting in the 1997-98 season, 5-time undefeated champions also win a new car.
Any winner of the Teen, College, or Seniors tournament automatically qualifies for the next ToC.
If fewer than 15 have automatically qualified, the highest-scoring 4-game winners qualify, to a maximum of 15.
If there are still fewer than 15, then the highest-scoring 3-game winners qualify. This hasn't happened very often.

In early years, the Tournament of Champions was held each November, starting in 1985, and the qualifying period lasted from September to July of the previous season. Later, the qualifying period was extended right up to the week prior to the ToC.

During the 1997-98 season, the ToC was moved from November to February (switching places with the Teen Tournament), so that for that year the qualifying period was a little longer. The same thing happened again in 2000 when it shifted from February to May.