well there's a handful of games that don't require insane percession but obviously with an issue like that its kind of funny in a sense to be getting a game system that's built around replicating movement
i understand the sense that the wii is by far the most kid-oriented system, and you will definitely find games he can play, but i'm sure he'll still get frustrated at times, it's just the way the system is designed and the way more and more games are starting to be made to make use of the hardware
i liked super paper mario, its a combination of old 2d mario, puzzle solving, and a lot of text reading (though the writing is superb), motion control is basically non-existant, save for pointing at the screen a few times to show doors or the like, and basically control wise is played like a NES Mario game for the most part, he shouldn't have to many issues with it (plus the game isn't difficult)
the fact that most solo-player wii games aren't that hard means he shouldn't have to many issues with probably the majority of them, but depending on how bad it is you may want to stay away from the obviously more motion oriented games or twitch games (like wario ware which is not only twitch but very motion oriented when it comes to the wiimote)
