Oda appears to be highlighting the main forte of each combatant. I’m loving the different ways to damage Kaido’s insides, it isn’t as simply as all the rooftop Supernovas having Advanced Internal Destruction Haki upgrade and I think that is great. It gives an uniqueness to each of the Supernovas and what they bring to the table.
Luffy’s the most well rounded. He’s tanky, he’s mobile, he’s powerful, and he’s fast. There doesn’t appear to be any real holes with him, which is why he’s the glue that keeps everything together.
Luffy of course has the internal destruction Haki upgrade which makes sense for him given he is a straight up brawler and we had an actual side plot of him learning it unlike the other Supernovas.
Zoro possesses the most deadly attacks. He can potentially end this in just a few blows should they connect, but he lacks the mobility to get around places, as proven by his reliance on Law, or inability to dodge Linlin’s attack mid air.
While Zoro hasn’t cut Kaido yet I think it is clear to me that Zoro possesses basic Advanced Armament like the Red Scabbards and doesn’t need internal destruction because he will be able to cut much deeper than the Scabbards because he has Enma. I think it will be called back to but Zoro first tapped into basic Advanced Armament in his fight with Mr 1. So Zoro is using his own skill while also harnessing the Haki power of Enma to straight up cut Kaido without the need of internal destruction. This is the closest to Luffy’s way to hurt Kaido but still unique given that Zoro is cutting while Luffy is punching.
Law’s the closest thing to a cleric. He helps get fighters away from attacks and transports the none fliers to their targets.