Let us report people for teaming.

I'm assuming you're talking about 2 completely separate teams working together to win?  I've considered that this might be happening, but it will be very hard to call out those teams doing it.  The only thing I could think of, in order to catch this type of activity, is to keep track of the teams joining, or trying to join, the same servers repeatedly.

This will be an extremely long shot to catch.  Now, what type of punishment should these type of players/groups receive?  Ohhh boy, I'm not even sure where to begin on that one either.