Please stop joking about Forrest Gump 2. There really is a sequel book written and I had the grave misfortune of reading it. It was, and always will be, the worst thing ever put on paper. It's really not a joking matter, I try to bury any thoughts of that book into the deepest recesses of my brain and you're activating some PTSD. Seriously, please and thank you.
As far as biographical MMA film... I, and everyone else here, would watch a movie about Megasoup. Some may deny it, but it's a train wreck we'd all tune into.