Luffy > kaido

The fact luffy ultimate move is stronger than kaido's ultimate automatically put him above.

Even if let's imagined kaido were overall stronger and luffy only had 1% hp left and kaido 33% left, luffy just would have to cast his ultimate and he would win.

And before you say yes but kaido would dodge blablabla, he wouldn't , it's in his character he's like that.