Luffy's acquired plenty of powerful forms which have come in all sorts of weird shapes and sizes, some looking much better ...
Luffy recently underwent ... Luffy's mind while in Gear 5, meaning he must choose his battles wisely. Shanks has always been one of the most important background characters in One Piece.
That said, even with the power of Gear Five at his side, it is hard to say whether Luffy and the Straw Hats will truly be able to defeat Blackbeard and his crew of powerful, devil fruit users.