You should get him Animal Crossing, if he doesn't have it. It's just like Oblivion, except instead of people, there are cute animals. And instead of fighting, there is bug-catching and home decorating.
(You know, everytime someone makes a thread like this, I'm reminded how narrow the GameCube's library is. Great if all you need is Nintendo games (and really, what else do you need?), pretty mediocre if you want anything else. Just one of the many reasons I'm looking forward to the Wii so much.)