Haruno Hyuuga Yamanaka
Member
This ^I doubt getting allies would be a problem for Luffy, just look back at what happened in Impel Down.. but where do you get the idea Yonkou need a fleet? Shanks only has a rather small crew himself and hasn't shown any alliance with other pirates like what Whitebeard has.
Only Whitebeard and Kaido (Big Mom is unknown) have large fleets. Shanks doesn't, he only has his crew, the Red Haired Pirates, with Benn, Lucky Roo, Yasopp and the others. So, fleet isn't a requirement for Yonkou. As someone else said up there, Roger was the Pirate King and had just a little crew and one ship, you can see this when he clashes with Shiki in the Strong World OVA.
And Luffy's not planning on being a Yonkou anytime soon, he wants to be PIRATE KING! They are two different things. And as someone else said up there, Roger was the Pirate King and had just a little crew and one ship, you can see this when he clashes with Shiki in the Strong World OVA.