I took a debating class in high school and this was something we did frequently. I loved it. If I remember correctly (and it's been well over two decades), the only rule was that you must argue the position as if it were your own. You could be called out if enough people thought you weren't giving it your best.
"I think younger workers first of all, younger workers have been promised benefits the government promises that have been promised, benefits that we can't keep. That's just the way it is." George W. Bush, May 4, 2005