Killer B, regular Bijuu's are much weaker without a host seeing as how deidara was able to 1 shot the 3 tails, if a bijuu is that much weaker without a host and 8 tails without a host stalemated, then i'm sure with Killer B, one of the most skilled Jinchuuriki's out there can win.
Tough one but i'm gonna go with 3rd. Dude is a tank. Other than biju dama, dude has nothing strong enough to hurt the Raikage. Plus he's probably faster.
considering the 8 tails by himself was able to stalemate the 3rd raikage, i would assume be could beat him. bee is a perfect jin and as a perfect jin he is stronger than the hachibi is alone. be also has his own skills as well adding to that. bee has to take this.