Is it possible at all to play online vs your friend? I can't find a menu that let's you start up a lobby or something.
The only way is you to enter the rivals mode and pray you get in the same lobby as your friend, if you don't, go back to channel 1 and then back to rivals. ps: channel 2 could be easier to match up. ps 2: sometimes is better to enter at the same time in the rivals channel as your friend and sometimes one at a song for example. in my experience it depends.