If it was in the UFC and I had 6 months to prepare (off my own dime) I would fight anyone from 135 to 170 weight class. I weigh around 170 walking around and I can cut to 135 if needed. I'd do it for free for the opportunity to say I did it, but I would prefer to make $10k off of it.
I'd cover up really well backing up against the cage, and when they close in to try to slaughter me, I would unleash the best left hook/right uppercut combo I have in my system. If they were still standing, which is obviously very likely, I would probably proceed to have the shit beat out of me.