Got them all, but I'm not playing much online at the moment.
If you want to play with a member of this board, you'll need to exchange friend codes (and, in the case of Animal Crossing, a note of your town & name IIRC) and enter them on your DS Friends list for that game. Then, both go online at the same time & search for Friends. You should find each other and be able to set up a match. AC works slightly differently - one person will invite another into their town - but it's pretty simple to figure out.
If you want to add me to your Friends lists, my codes for each game are:
Tetris DS
6939 8002 3283
Mario Kart DS
3479 5238 0810
Metroid Prime: Hunters
0730 8278 2677
I've managed to lose my AC cart, but if I find it I'll post that info here as well.
Tetris is a blast in Wi-Fi mode, and while I haven't really put in much time in Metroid Prime: Hunters, the little I have played has been great fun. Mario Kart is a little basic, but Wi-Fi in that is still a fun experience.
