Well, footwork is highly important. If you want drills, pretty much make up your own and just have the goal of acquiring good multiple opponent skills - good footwork, keep moving, speedy strikes, hard strikes, and get out of there as soon as you can. First drill is to make sure you can move so your friends have to know how a gang usually attacks - it is never one one one. Have one drill where they run at you and another where they are already upon you. The best footwork is to have one opponent block another so you have to angle them in (its like using one to setup a pick on another) and if you keep moving then you can make it so they attack one at a time despite their best wishes (which obviously means also that you hit the one closest to you). Practice in small spaces. Remember that your main goal is to get out of there so do that as soon as possible (think jackie chan or tony jaa). So have a bunch of friends gear up (helmets, chest, gloves, shin, groin, foot protection) and you really put a whooping to them (still be careful you don't get caught in the heat of the moment). Add a weapon that you might find in certain locals, if you've taken fma, not too unlikely that a stick may be laying around or you put a rock in a sock, etc. Be creative and realize that depending on the abilities of your attackers you may not always be able to get out unscathed, so your main goal has to be to run even if that is the first thing you can do before the situation even escalates (so also practice running a couple of miles full speed
).