It’s literally not. If Zoro said that they’ve been attacking BOTH Big Mom and Kaido; then that’s literally what’s been stated in the canon story. Nothing you say is going to change that fact lol
Kid was the one saying none of their attacks were working. That statement doesn't mean everyone attacked Big Mom.
Kid statement doesn't mean Zoro or Luffy used ryu or internal destruction haki.
Luffy could beat any Commander post-WCI. That's being 5th Emperor means and it's why Oda made his bounty higher than Marco/King.
He doesn't need Ryou, because his physical strength is Tiers above Zoro. Zoro is just more lethal.
You're wrong about the fifth emperor part. He was called the fifth emperor because he entered an emperor's territory, beat two of her commanders, and got the better of Big Mom, a Yonko and escaped.
Contrary to belief, Yonko don't go around challenging other Yonko or evading each other's territory. Luffy's WCI feats are very impressive.
How would Luffy beat King when he has the greater defense than Kaido? Answer, he wouldn't.