For now, only the first party games will be able to have online support. All the other games made by 3rd party developers will not have online support til next year. So there's very few games than can play online at launch.
I'm sure many of them will have downloadalbe updates for online support. I'd say the main problem is that online probably isnt finished yet, since they haven't really told us much about it. Hopefully we'll get some answers soon, but until then, it's just wild speculation.
i think wii sports shud b online,but it int. jus imagine beating the crap out of a boy from anutha country in wii boxing or pitching him out in baseball lol