Needless to say the online portion of this is fairly dead, so chances are you will have to boost. These matches are done in ranked and shouldn't take any more than an hour per person if done correctly.
First, the winning player hosts the match. The one losing can do a quick search (unless they somehow run in to somebody else) and connect with the partner. Then, once the character selection screen pops up the loser will press start and exit game. Rinse and repeat for your victories and then swap. It's worth noting that the winner can simply turbo the A button if they have any controller with this function, as they'll continuously host matches for the other person to quit out of.