Hades Cup

The Hades Cup is the fourth and longest-running tournament at Olympus Coliseum in Kingdom Hearts. After the cup, Phil puts up the trophy in the Lobby. There is a boss in every tenth seed, and after defeating each boss, your progress is saved so that you can continue from that seed even if you lose the cup.

The Hades Cup also reappears as a mandatory tournament in Kingdom Hearts II, during Sora's second visit.

Kingdom Hearts II
After the Underdrome is accidentally opened by Sora, Hades begins preparations for the second Hades Cup. During Sora's second visit to Olympus Coliseum, Hades forces everyone to participate in the cup, including the weakened Hercules. Hades had also stolen Auron's free will in order to force him to kill Hercules and Sora, but Sora manages to reclaim Auron's free will, and the heroes defeat Hades together. Much later on, Hades opens up the Paradox version of the Hades Cup, which has the traditional fifty seeds.