For those fortunate enough to be able to double box or have a dedicated friend.
First off,in the first screen, change the server to Japan West or Asia by pressing
(those servers are hardly populated)
Both players will have to search for the same gamemode seperately, if you'll invite the other party they'll just end up on the same side.
You'll be able to start a match with just two players. It will search for a while but after a minute or so it will start the countdown. You can win the match by having the opposite party quit out and rejoin after the "Victory" message has appeared. This way you can simultanously go for the 50 wins per gamemode.
I also suggest to remove all DLC packs so you won't have those maps in rotation. You both have to remove them, otherwise you wont be able to find eachother.
You will be able to check your progress under Personal stats > Levels