ive never done that, ive done one on group but never group on group and ive only done sparring in one on group never full contact. its fun but hard and strategy, tactic and footwork are extremely important. i would think 2 vs 2 would be the best place to start as a progression to larger group fights. what are some arts that stress group fighting? krav maga comes to mind. but again what ive seen is primarily 1 vs group.
For whoso comes amongst many shall one day find that no one man is by so far the mightiest of all.