Random Point System

I am currently working on my final project for my introduction to programming class we are using Python. I wanted to make a pong game but with a twist. Since I figured that normal pong is overused, I wanted to make it so that there was a different point system.

That said, I want to make a point system that will randomly add and subtract points to player a and b and have them switch scores at least once a game. Any advice on how to do it?