I think what people don’t realize is that Luffy names most of his moves after cool or impactful experiences he has.
- Pistol – “My fists are like pistols!” Also I believe Lucky Roo’s pistol has something to do with this. This is is signature opener in almost every fight.
- Bazooka – He thought Sabo died to a bazooka. Up until the timeskip it was pretty much his finisher for almost every low-to-mid-tier fight, and even some of the higher tier ones.
- Storm – It hadn’t rained in Alabasta for years. Luffy defeated Crocodile with a storm.
- Pinwheel – His failed attack in Arlong Park after seeing Genzo wearing that hat. I believe (could totally be wrong, here) that the reason it failed is because the pinwheel was meant for Nami, not Luffy.
- Haki-Related Attacks – Almost every Haki-related attack, particularly those in Gear 4, is named after an animal: Luffy learned Haki by sparring with powerful animals. Even Red Hawk – his homage to Ace – is also named after an animal.
- King Kong Gun / Leo Bazooka / Culverin / Python / Red Hawk / Rhino Schneider / Black Mamba / Etc.
- Tying to Red Roc(k) – As many have pointed out, this is an upgraded, Gear 3 version of the Red Hawk. Roc rhymes with Hawk, and [the Roc] is a large, mythical bird of prey.
- However, what I think everyone missed is that previous to this, Oda spent roughly two full pages mentioning Raizo, how Luffy hasn’t forgotten him, and the flashbacks to him and other events surrounding Kaido’s involvement in the suffering, pain, and even death of others.
- What was Raizo tied to in the whale? What major artifact was it? A Road Poneglyph. What is a Poneglyph? An indestructible rock slab. What color are the Road Poneglyphs? Red. Who made the Poneglyphs? The Kozuki Clan.
- Luffy literally hit Kaido with, and named the Red Roc(k) attack as a tribute to: Ace, Raizo, the rest of the Scabbards (and Momonosuke, and in a roundabout way, even Oden), the Minks, and, quite frankly, all of Wano. Oda loves his puns, and this fits perfectly.
This is what the giant wall of flashbacks is pointing to. This one attack, that opens the fight, was for all of them. The fact that Luffy hit Kaido in the exact same spot that Ace hit the statue, as well as the local sea monster from chapter 1 is just icing from Oda.
*Theory by LedgeEndDairy