@DesertSpada:
Blackbeard didn't trash Shanks. He scratched his eye. Now, this proves that he's very powerful indeed but there is no way that his crew could take on Shanks's. The Yonkou have enormous crews that are in the thousands while Blackbeard would only have a handful. I also doubt many people would go over to his side from Whitebeards crew because of their fierce loyalty to Whitebeard. So I really don't see Blackbeard becoming a Yonkou.
Also, so far, if anyone the top people in Shanks crew are Yassop, Lucky and Ben Beckham. Rocktar is still a rookie so he only has menial duties, at least from what we've seen.
Not true, or atleast not proven to be true. The only emperor with a fleet crew we know off is WB. Shanks and the other Yonkou could easily have crews that can fit on the ship.
Also, this theory is plausible, and if Shanks were to lose against him it would simply give Luffy another reason to fight BB. But the way I see it is if they do fight, BB would probably kill Shanks, sine he is pretty close to ONe Piece and PK status, BB wouldn't turn shanks in because he has already collected enough bounties and reached the level as a shichibukai. All that is left to do is kill Shanks, and plot-wise I don't think Oda will kill Shanks until he re-unites with Luffy. So a Shanks x BB battle is possible in the future, but has nothing to do with the crews "pairing up well" because they don't. Basically any crew can pair up well with BB.