[@Halvtand]

I don't know. Two teams that have already lost members and are in a weakened state so soon after the exam started are going to be thinking of the best ways to ensure that they get through the exam, either by surviving it or improving their odds to pass. And from what I can tell the only real passing grade you need here is to make it through to the end. If survival is the only real requirement, then there really isn't much of a need for teams to fight each other. 

Considering that the Chuunin exams had each team carry a scroll and required them getting a second, different scroll from one of the other teams that forced conflict, considering the only goal for this exam seems to be 'Don't die' and two teams are going to pass, two teams teaming up makes a whole lot of sense. And since they are all made up of different villages, it's more a chance of 'Can we trust this bastard?' then 'Can we trust this team?'.