With Kaido demolishing Luffy, it seems like Luffy has an insurmountable mountain to climb but this is just great writing by Oda.
Oda only has a few categories that contribute to power levels so breaking it down makes it easy to see what area Luffy can make up the difference:
Haki
Oda loves misdirection and Advanced Haki is another perfect example of this. With all of Luffy’s recent training he is repeatedly trying to point fans down the road of Advanced Haki being the solution to Luffy beating Kaido.
Devil Fruit Abilities
The level of mastery is key since we have mastery of the basic devil fruit abilities (Luffy is the best example of exploiting the unique traits to create the various Gears).
Awakening
Clearly this allows for astronomical power-ups. Potential weakling guards become probably second in all of Impel Down to only Magellan, Doflamingo gains a perfect defense/offense combination, and something most fans might have overlooked: the MASSIVE destructive power of Aokiji/Akainu to seemingly permanently change the environment of Punk Hazard. With this last example in mind, there is no other option for Luffy’s final major power-up.
Physical Capabilities.
All physical factors related to “combat capabilities” (power/physical strength, destructive power, endurance, speed, agility/evasiveness, etc… This can be trained with the right exercising, but the level of “natural talent” makes a huge difference on the starting point (Luffy/Zoro/Sanji all started with natural talent compared to the rest of the crew).
Furthermore Luffy’s ability to figure out an opponent’s weakness throughout the series will continue to be key. Unfortunately, Kaido will be the most complex puzzle to figure out which is exactly why Oda made multiple comments on not knowing how to handle the Luffy vs. Kaido fight.
I do want to continue on one aspect from the above in the theory. Luffy already is very close to “Yonko level” for physical capabilities in my mind. The residual kinetic energy of Doflamingo destroying a huge chunk of Dressrossa. The destructive power of King Kong Gun matches Aokiji/Akainu’s final attack. Luffy is getting a power-up to his physical capabilities.
With Luffy already having adequate strength/destructive power (it previously couldn’t penetrate Kaidou’s mastery of defensive Busoshoku). Just in case anyone overlooked this minuscule detail, Kaido has complete mastery of defensive Busoshoku:
It is not shading. Every single attack Luffy throws has the minimal amount of defensive Busoshoku used and this is the main thing that stops Kaidou from taking any damage. This mastery in conjunction with implied foresight level Kenbunshoku negates all non-advanced level haki attacks. In theory, maybe there is an “advanced defensive Busoushoku” technique. The “haki barrier” technique is implied to be this but we don’t see two evenly matched opponents square off. In all other instances, offensive haki has major advantages over defensive haki, so until we get real evidence, this is up to debate and I can argue either side. Even if this does not exist, there’s still an easy negation: Kaido throwing his own advanced haki attack. Kaido will have greater physical capabilities than Luffy, so Luffy takes damage in every exchange. Kaido has been recently been shown to not be a complete meathead, so he will figure out such a simplistic strategy that has a 100% success rate.
Thus, the only other empty category (legit plot wise too) is an Awakening and this has to be the answer because it is the only thing that allows for the necessary astronomical power-up.
All of this should perfectly fit, so now into the meat of the theory. What is necessary to unlock an Awakening?
We’ve only seen a handful of awakenings, but people like Doflamingo, Aokiji, and Akainu do have one thing in common.
They’ve all had their fruit abilities for years and years (potentially decades). I’m thinking there is a year/duration limitation in that the DNA mutations from the akuma has to reach a necessary threshold. So from a scientific standpoint, maybe every single cell in a fruit users body has to be genetically altered and this is just a slow process. This is the opposite of the science of cell proliferation but…manga logic. We’ve got a guy that can stretch any body part 100 gomu gomu so Oda gets to make up whatever he wants.
The biggest support for this is Lucci making multiple cameos. Only characters that have future roles stick around. If Lucci is getting screen time in Stampede, he’s got a HUGE role to play. Tag teaming with Luffy to take down Kaido fits this.
Obviously, an old enemy suddenly being an ally is a huge deal considering Luffy completely ruined Lucci’s impeccable reputation. How/why would Lucci side with Luffy. Kaido/Big Mom’s alliance is THE biggest threat to the world. CP0 operates on country changing level threats. Big Mom and Kaido alone are CP0 level threats. The alliance immediately becomes CP0’s top priority to weaken. Thus, even though they hate each other, the mutual greater enemy forces the alliance.
If that isn’t enough, I’ve got more:
When Law escaped, someone with a cape let him out. Someone wants as much chaos/pro-Luffy situations. Yes, this could be Denjirou or Drake. However, there is one other key panel in all of this.
When Orochi meets with CP0, there is an additional spy watching them from the next room. They are obviously upset at Orochi since the text bubbles overlap their angry eye. Context implies a CP0 agent was assigned to be a spy and monitor the already huge threat of Kaidou/Orochi’s alliance. Lucci is the only person that fits all of the breadcrumbs (don’t forget about the Stampede/cameo aspect).
As we know Wano arc is based on the kabuki. So the third act of the Wano Kuni arc being a “tragedy” fully fits kabuki plots. With only advanced haki, Luffy is 100% guaranteed to still get his butt handed to him…easily too.
Bomb time! I’m thinking the combination of an awakened Luffy (Gear Fifth?) AND an awakened Lucci will be the tag team that fights Kaido in the real climax of the arc.
To go back to Oda’s comments on how he couldn’t figure out a fitting way for Luffy to defeat Kaido, this is probably WITH the combination of an awakened Luffy AND an awakened Lucci (Lucci had already made two manga cameos at that point). Kaido is literally such a beast that two legit powerhouses in the New World were still struggling to take down Kaido in Oda’s mind.
And this is with them having pretty good chemistry. Not only have they fought each other (they know each other’s strengths and weaknesses and are both strategic enough to fight to set up the other for what they excel at), but the time spent training together for Luffy to get his awakening will be key bonding. Luffy is a dunce. He will struggle at picking up whatever “training” aspect is necessary. Lucci will have to beat his own head with all the frustration. But like every other Luffy relationship, that’s just how it goes.
*Theory by Seiryu