Oh yeah SSB would be awesome on DS over WiFi. I don't really have any games I wish were WiFi at the moment, but I hope future games will use lobbies instead of matchmakers. Like you can create a game, then it shows up in the lobby and people can join. Lobbies should sort the servers according to game type, ping, and other settings. That's why I don't play MKDS much because I hate matchmaker style online games.
Ah forgot to say this, hopefully there will be a nintendo network where you can download updates and patches for game through the main screen and maybe some updates will include an online mode.
It LOOKS interesting but believe me, it's not! I downloaded the demo on EB Games once (one of the DS's had the full game, so I sent a demo from the DS in EB games to mine)
I would have love Meteos even more if it was online!!