If players in TeamColor died, declare opposing winner?

I've been struggling, and trying to figure out how I would be able to properly do this. Does anyone have some advice? I'm basically making a Minigame place, and in the Main Script I cannot figure out how to identify a winner on a certain TeamColor when the opposing teamcolor has died and returned to lobby. Can anyone help? Much appreciated.

*EDIT: I am NOT asking anyone to create a script for me, just a little help on the concept. I do in fact know how to script, and understand basic terms.