Story literally has him to beat kuzan
No, it doesn't. There's literally nothing indicating that. People have always made assumptions that Oda later debunks, like the idea of Sabo stalemating two Admirals.
In that panel where Kuzan is featured, why did Oda place him there? He could have just shown Teach, and we would have assumed Kuzan would fall under him, just like Mihawk with the SHs.
But Oda made sure to present Kuzan as an individual, not as a member of the Blackbeard Pirates. He won’t be a part of the BBP later on, and he won’t be the antagonistic character people think he will be.