Paper Mario: The Thousand Year Door(best rpg made)
Super Mario Sunshine
Luigi's Mansion
Animal Crossing
Mario Kart Double Dash(could've been better but good)
Super Smash Bros. Melee(of course! what really started SSB off on a good foot)
Mario Party 4,5,6,7
Kirby Air Ride
Sonic Adventure DX(not a smiley←)
Sonic Adventure Battle 2
And Wario Ware :D best games ever on GC for me :P