Show off Achievement
Win 750 fights
This is cumulative, and is counted from any campaign levels, submarine levels, daily challenge fights and arena fights. The campaign levels do not have to be unique, you can grind the first level over and over again for a guaranteed win if you like. This will take a long time to get due to the fact every fight you do costs power, so you need to wait for power to regenerate between fights in real time. You will probably be there or thereabouts by the time you get the rest of the achievements.