Alright, so the scene is a bar. The fighters down for a night of drinking, so the two are smashed and also probably at ease, so lets throw Ram Man's helmet out of there (still has the metal plate on his head).
Lets say both fighters are at thier peak in terms of inebriation. I mean Ram Man could probably take more (being HUGE) but for my purposes we'll say they're equal. Dunno how they are when they're drunk, but they're fighting so I guess they're angry drunks.
First off: Ram Man is HUGE. So much to trip over. He'll be wrecking the place right off the bat, and FISTO would probably be getting out of the way most of the time. Still...FISTO is a man of action (we can assume this because he had a giant metal fist attached to his arm stump - this is not a wait-and-watch type of guy) so he's going to be charging into the fray while Ram Man is charging him (and knocking everything over in the process). FISTO probably won't know better to get out of the way, but Ram Man won't be charging at his fullest. Chances are, FISTO will throw a punch right at Ram Man's charging head. Ram Man's metal plate still takes the blow, since I doubt FISTO is throwing his strongest punches either.
This will probably go on in a similar fashion. Ram Man keeps trying to charge or grapple, and FISTO will come out swinging every time, perhaps grappling when the two manage to get ahold of each other. That's where the key is, I think. Ram Man will friggin' toss FISTO when he gets ahold of him. Eventually I think that'll knock some of the drunk outta FISTO, but while he's getting up I assume Ram Man's final charge will send him through the wall and out into the alley.
They both lose out on paying for the damages, but in the end I think Ram Man is too much of a drunken wall of power to take down when the opponent is also drunk.