I didnt want to get involved in this one mainly because its a waste of time for Tank to be fighting, but here goes..........
Tank is a marquee name for some reason, but the guy is no MMA fighter. A well schooled submission fighter could have his way with him any day of the week, he has nothing to offer except a powerful punch. His skills are zero, his cardio is pathetic and he has a chin that is susceptible to being hit. He is a strong mofo for sure, but benching 600 and curling the 150's doesnt get you anywhere when you are opposite someone with well rounded MMA skills - i.e. a primed Mir or Belfort. Basically, hes a bitch.
Butterbean however is a proven striker and can punch the shit out of just about anyone. Hes a big fat girl for sure, but he KNOWS how to use his body to KO people. He has been subbed, but there is no need for him to worry about that if he is fighting Tank. All he has to do is what he does every day, work Tank into a position where he can knock the shit out of him.
My verdict: Butterbean by brutal KO inside 3 minutes (maybe even 2)