If you want to play a regular match, you'll just have to join him in progress (or he'll have to join you in progress). And then half the time you won't be on the same team. It's infuriating.
You can't party up and matchmake until A. You hit level ten and B. Get rank B-.
Even then you can only group up for the sweaty League Play mode, not Regular Battle. It's terrible. Nintendo needs to enter this decade when it comes to online multiplayer.
Glad I'm not the only one having some strong feelings about the big restrictions on team play.