Hey, I'd just like to say first, that whoever thought of the idea of 4P is a complete genius! I've been able to rake up my rank now.
Good tip is to team with a good player... And be a good sport yourself. Never tag your team-mate unless you are low on health, it's important to let your team-mate get some action, but you need to be in there too. Oh, and I advise to use Ryu's specials... Very handy indeed.