If he did in fact get into 300-400 street fights it is very unlikely he would be around to talk about it. There are a lot of dudes out there that are bigger and badder than Marlon. The chances of surving that many street fights are slim to none. It's more likely he got his ass kicked 3 - 4 times though.
He is a tool and he is going to get a beat down when he fights on the show.