Whatever one you play, get into it. It's not any of the sports because there's a lot of waiting. Multiplayer games lower your time in the "game field" and lower your exercise. I think there's a wii dance, which is pretty good. Unfortunately I don't think the wii games are vigorous enough to help you lose weight. Maybe if there's a wii jogging one or something. Whatever makes you exercise more consistently in the time frame you're working out.
Wii fit and there is a new game out called "the biggest loser" which is based off the show, it tracks your calories and workouts, sounds pretty good to me. The indoor challenge is probably pretty good, and DDR is really good I find because dancing is the best way to lose weight and I know when i'm done with that game I have my sweat on.
hahaha i woudn't really recomend wii doing the actuall sport is many times better, but if you were playing the wii and you wanted to lose weight the best thing you could do is play some like wii fit but most importantly follow through the moves don't just move your wrist when your playing tennis but swing your arm (i move my wrist =D)
i like the idea of losing weight on the wii but really, i don't think it works. just try going for a jog, go swimming or something that raises you <3 beat.
there is this dance game like this mambo game and it aperantly helps u loose weight. peace, love, happieness: flowerpower123
and sorry guys I lost the game.