Red Hair Pirates
Shanks is a bit of a given as a future ally and proponent of Luffy taking the mantle of the Pirate King. It’s very safe to assume that once he determines that Luffy has surpassed him, he’ll enthusiastically cast his lot with the Straw Hat Grand Fleet as one of Luffy’s greatest supporters. Given the party he threw when Mihawk told him about Luffy’s growing notoriety and showed him the Straw Hat bounties, Shanks is practically yearning for the day he gets to place himself behind Luffy.
Big Mom Pirates
Lots of wishful speculation about Katakuri joining the Straw Hats. But even if he doesn’t join the crew, one thing Katakuri did do is recognize Luffy. In the event Big Mom is toppled and Katakuri assumes command, is there any possibility he might at least join up as a member of the Straw Hat Grand Fleet? He’s taken the step of showing Luffy the respect he knows Luffy deserves. Would it be too much more a step to recognize Luffy as the man who WILL become King of Pirates, and therefore the man he’s willing to submit to?
I know they’re not a Yonko crew anymore, but there are a bunch of beastly dudes floating around out there who had nothing but love and respect for Luffy’s brother, and saw Luffy fight his heart out, pushing himself to his absolute limit, to protect one who was dear to him. They witnessed his display of the Conqueror’s Haki and saw his raw potential. One of Whitebeard’s final commands to his men was to “Lend Straw Hat Luffy all of [their] strength.” While this was in the context of saving Ace, I think it’s entirely plausible that the remnants of the Whitebeard Pirates will view Luffy in the same light as Ace. Once the Straw Hats find Marco, I think we’ll see the mighty Whitebeards uniting again under a new banner.
Yeah so I’m not about to speculate that Jack will suddenly want to join the Straw Hats. What I am curious to see is if we find another Katakuri type in their midst—that is, someone who is surprisingly honorable/respectable among a crew of murderous monsters. I previously would have assumed otherwise but after some of the gems that have shown themselves among the Charlotte family, it wouldn’t surprise me to see some beasts in Kaido’s crew who respond to Luffy similarly. Obviously this one is pure speculation since we really haven’t seen much of the Beasts yet.
*Theory by FacelessShadow