Blackbeard just gave Shanks a scar. There is no reason to conclude that he was defeated by him.

Quote Originally Posted by poopdeville
In short, none of the current super strong guys are a match for Blackbeard, which probably means Luffy will have to fight him to be PK.
How do you come to that conclusion? Blackbeard has been runnning around, trying to prove himself as a person worthy enough of becoming a Shichibukai. I really doubt he is the strongest one, as of now. But I do agree that he is a strong contender of being the Pirate King in the future as he has the "Luffy attitude" and is also a D, which means quite alot in this manga.

Blackbeard is slowly making his way upto the top but he is not there yet.