It takes about 20 wins with 1 character in order to get to level 11. There are two ways to go about with this.
1. Do this legit. Be warned, the community for this game is scarce and for the rest that play this they are really good.
2. boost it with a friend.
I did #2 because I stink playing versus. Go to Network and start a ranked match. Hit entry and you should be a lobby waiting for a opponent. Your boosting partner should then search for you and join. Choose one character you want to use. I say one character so it is easy to keep track of your wins/ matches played. Alternate wins however you want to do it. All in all, it should only take a few hours for both people.
*3/8/2017 update.
It seems as though people cannot access ranked matches anymore. I checked to see if it was true and it seems like the ranked matches do not work. This is weird since there has been no news on any closures, maintenance or delistings. The last known ranked match was played on 12/17/2016 for the game so it must of shut down then. I searched online for any news and cannot find any reason why this is happening. It seems as though that this achievement is UNOBTAINABLE at this time. If the status changes, I will update when I know more.
*5/23/2020 update
Looks like ranked matches are back online again since people are commenting and unlocking this achievement. It is attainable once again.