How do I make spawn points random

I just made a duel map in which 2 people face off and the winner goes through a teleporter to another area and faces off with the other winner. There are 3 areas per round and 10 rounds. The problem is that each round the matchups are the same because everyone spawns in the same spot they did for the first round. I was wondering if anyone knew how to make it so that what initial spawn point someone started at is random for each round so that you face a random opponents. Thanks