Zelda Wind Waker, Zelda Twilight Princess, Fire Emblem Path of Radiance, Super Mario Sunshime, Luigi's Mansion, F Zero, Star Fox Adventures, Tales of Symphonia, Metal Gear Solid: The Twin Snakes. That should be a pretty good start, lol.
I'd also add Rogue Leader and Eternal Darkness. It was the original home of Viewtiful Joe and Resident Evil 4 (RIP Capcom Five). Also loved Beyond Good and Evil. Though it was multi-platform, it felt right at home on the Gamecube. Same with SoulCalibur II.