Triwizard tasks are built for three pads in Harry Potter and the Goblet of Fire, EA's 2005 tie-in to the fourth book and film. The GameCube version supports three players in the dragon, the lake, and the maze, with Harry, Ron, and Hermione sharing the challenges.
The cup's year is not a school roam like the earlier tie-ins. It is a run of set pieces, and the three-player support is what the cube build adds to those tasks.
A dragon over the castle and a dive in the lake are co-op problems. The graveyard still belongs to the story, but the pads are why this tie-in feels like a party.