Chief Mendez
Smash Master
WiiI'm looking for a decent game I can play cooperatively with one to three players on either the Gamecube or the Wii. I'm not a big fan of shooting games, but if there is an exceptional shooting game, I will probably enjoy it. My friends and I just finished Phantasy Star Online EP II challenge mode, to give an example of what I'm looking for. RPG's are good. Sports games are fun, but only if they have a create-a-player option. So, what game should I get?
Mario Strikers Charged is quite a good game--don't let the fact that it's soccer scare you away, as it plays more like an arcade game than any kind of simulation.
Virtual Console - Toejam & Earl is a really fun platformer by itself, but is even better with a friend. Though the gameplay is a bit out there...
Virtual Console - Legend of the Mystical Ninja is, like TJ&E, a great game in single player, but gains alot with another person along for the ride.
Mario Kart Wii = a given. The Battle Mode was completely ruined, but the core gameplay is still as fun as ever.
Naruto: Clash of Ninja Revolution is basically what Smash Bros. would play like in 3D. Even if you don't like the series it's based on (and if you do, it's a must-buy), it's still an extremely fun 4-player fighter.
Gamecube
Phantasy Star Online C.A.R.D. Revolution plays differently than the normal PSOs, but is still tuns of fun.
Gotcha Force is what you'd get if you crossed Armored Core with Pokemon. You might have a hard time finding this in the wild though, so an online retailer is probably your best bet.
Custom Robo for GCN isn't as good as the Japan-only N64 games, but it's still worth the five or ten bucks it costs nowadays. There's tons of parts to collect and thousands of potential combinations, so you'll certainly be kept busy, if nothing else.
Geist is a shooter, but with a significant-enough twist that you shouldn't be worried. The single player campaign is middling at best, but the multiplayer mode is incredibly fun--one side plays as ghosts, while the other plays as ghost-hunting soldiers. The ghosts can possess elements of the environment (as well as the soldiers themselves), but can't wield any weapons. The soldiers, on the other hand, can set ghost traps, and are each equipped with ectoplasm-destroying weaponry. Though again, it's quite the rare find these days.
Anyway that's all I've got right now. Hope that helps.
EDIT - Also the Baldur's Gate game(s?) for GCN. Classic Diablo-style gameplay for four players = happy times.