Oda would have to pull weaknesses out of ass for Luffy to be able to beat the likes of Marco, Katakuri, Akainu, Kizaru, BB
He would have to create even more heaps of bs to beat them without haki, forget about Luffy how tf was Roger standing over all these characters with just a sword and a gun in his belt, or how was Shanks competting against Kaido, how would he stop Akainu's magma from melting his sword and the list goes on.