Experience is key
Both groups agreed that it would be a bit much for everyone to fight everyone, so they agreed to have just a single fight. Each group would decide on their strongest member to send out as their representative.
It had been a while since they had just been fighting for the fun of it, rather than with something on the line, so everyone was looking forward to it. After finishing their meals and grabbing some extra blood, they decided to head to one of the training rooms.
The good thing was that even if someone ended up injured during the fight, there was sufficient blood nearby to quickly heal up and recover as long as the injury wasn't too bad. They even had other things like 'meat' for those who needed it.
Xander, Timmy, Fex and Amy were selected to act as referees. If at any point they thought the fight was getting too dangerous, it was up to them to rush in and stop it. Nobody actually thought it would come to this, but still it wouldn't hurt to be on the safe side.