Your player level will increase as you increase the level of your characters, and it seems to be an accumulation of all your character's levels. So a very easy way to do this is to go through the Story mode with each character. There are only a few matches per character, and you can skip the scenes in between if you're not into the story, meaning with 16 characters you can be done with the whole story in an hour or two. Each character reaches level 8 or so by the end of their story, so you'll earn this trophy before you've finished all the character's stories, and you'll earn a few other trophies along the way. Then just finish the rest off for the all story mode trophy.