Proceed with caution. Here we go:
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1. No recklessness from the start
- Luffy acting impulsive in Udon, at the first meeting with Kaidou.
The solution: Saving FS, facing a Yonkou, Luffy should've instead realized that every possibilities of the Future if he try to fight Kaidou, is death. Not just his death, but the massacre for his comrades first (imagine seeing Zoro, Sanji, Nami, Robin, Law die in front of him, their bodies exploded into meat juice as Kaidou deathblitz them all, with just a single move, his speed to kill them less than a hundreth of a second.) and he saw his own death the last. This emphasizes both Luffy's FS and also Kaidou being WSC. The win-win solution for hyping their future battle.
That way, Luffy will wreck his own brain lightning-fast to bring his friends to some hideout in Wano first (before Kaidou closing in on them) instead of even encountering, much less confronting, the WSC directly. His friends will be confused as Luffy seem to know which way to go to and which direction to avoid in order to finally escape something that they havent even sense yet, which Kaidou's presence and attention.
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2. Proper individual preparation and self build-up
- Luffy is facing the literal Strongest Living Being. He cant just go wherever he want and fighting fodders and Ulti and Page 1 and Yamato and Queen etc, he is the last stand against Kaidou for Tonjit's sake. He shouldve preserved his strength, move as efficiently as possible in this arc. Only fight himself if its absolutely necessary. Which, with Zoro-Law-Kidd-Yamato backing him up, they wont let anyone near him. If King-Queen-Jack can be fought against 1v1, well Luffy shouldnt even participate in fighting them, and save his strength only for Kaidou since the start.
- Luffy is facing the literal Strongest Living Being. It is foolish to train in prison, after defeat. The wise action is for Luffy to train individually since the start of post-timeskip, in order to defeat Kaidou. Bring us a flashback of Luffy being oddly silent and locking himself in the Thousand Sunny's Captain Room, hours and even days after each arc battle. Against Hody, Doflamingo, Cracker, Katakuri. During which, he evaluate each of his strength and weaknesses, and constantly went under image training against the enemy he just beat, finding the best possible scenario to beat them efficiently to correct his mistakes...and more importantly, to do the third keypoint from me, that Luffy severely lacked, even when he should've made himself the best in the One Piece World regarding this:
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3. No Messiah and Destiny - instead generate Creative Process - Luffy's Power Invention.
If there is something really impressive about Luffy, it's his creativity to invent his own powers using whatever assets he possesses, into something really fresh, fun, and at the same time limit-breakingly powerful. Imagine using one of the most boring and weakest Devil Fruit, Rubber Fruit, and instead formulate Gear 2nd. Imagine seeing it at the first time. Even without proper process and hints, its application in battle was nothing short of incredible. Now Luffy should've trained his creativity and Oda should've (to some extent) depicted him as a boy that is hinted to be mentally exhausted, some time before each important battle. During his movement to reach Kaidou, while he shouldnt even participate in other battles...in contrast, his mind shouldve reeled constantly. Since he must push himself to formulate the strongest power possible, he cant relax since it's the WSC he will fight against. He shouldve told himself, its to protect everything. He can rest once its over. Its to protect everything. He can rest once its over.
During Luffy vs Kaidou, Nami or Zoro or someone shouldve told other alliance members like Scabbards, or having an internal monologue, that Luffy was exhausted before this battle against Kaidou even begin: since Luffy seemed to constantly invent and do experiment of his own fruit-haki-body-energy-mind etc to escalate his own powerlevel, and also constantly re-evaluating his own ideas on that, in order to surpass his enemies with his original ways.
This way, Luffy didnt need to emphasize the fated Voice of All Things as something to help him in dire needs, such as when Kaidou threw him down from Onigashima. Luffy shouldve faced Kaidou with his own original powers, maybe he managed to invented Internal Destruction as the result of his power invention? Instead of Hyogoro teaching him? That way it felt earned. Yes i'm looking for that feeling of Luffy earning something instead of taking that CoC specialization notion for granted.
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4. A rough sketch how i prefer the Raid War compared to the canon
Since the beginning, all the strongest fighters in the alliance goes all-out and attack Kaidou. No one can even touch him due to Dragon Force: Kaidou's permanently-active CoA that he obsessively trained and hardened for decades since infant, acting as a body armor, millions of times stronger than Bari2 No Mi. The reason for his title, World's Strongest Creature. No one can reduce his lifeless boredom, emptiness, no one can force him to move an iota from his standing ground. Until he senses Luffy's presence. Kaidou orders his subordinate to make way for the boy, and get away from Wano Country itself, to the seas, as far as they can. He also tells them that if they haven't finish the Strawhat Alliance by the time he's finished with Luffy, he'll kill them all himself.
With that order, the entire Beast and BM Pirates and alliance pirates sail to the ocean and continue the war as naval battles before boil down into group fights and 1v1s. Marco vs King aerial fight (flashy fireworks in the sky), Sanji and Law vs Queen with tricky sea battles and large scale attacks and object manipulations (ships flying and seakings flying everywhere teleported from and to the sea).
Kyoshiro (Wano's 2nd strongest swordsman) and Zoro, vs Orochi, whose Hydra form is actually very strong and resilient and also able to swim in the sea, even stronger than King, and also very cunning. Zoro also find that Orochi is apparently the best swordsman in Wano history, his sword techniques are far higher than his. Zoro can't even predict who will be the winner of a swordfight between Orochi and Mihawk if they are to meet in a battle.
It becomes an underwater battle between two swordsmen and Wano's strongest swordsman who is also a sea monster, creating seawaves as high as mountains, one hydra head being cut but regenerated, rinse and repeat. But Zoro manages to awaken demon spirit Takemikazuchi as the Lightning Sword Deity, his unique CoA manifestation, and cut all nine heads at the same split second), then both of them recruit Yamato.
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Yamato vs BM. Strawhat and 9 Scabbards vs Flying 6 and Numbers etc. Many casualties, many deaths from Heart Pirates, Kidd Pirates, Scabbards and Minks, many betrayals and backstabbings and double-agents etc. If we want some more gutpunch, Chopper, Nami and Robin die after being tortured by Beast Pirates and CPO Agents. Replaced by Law (who is left alone in Wano since all of his crews are dead, so he enters the SH crews as a surgeon), Jimbei (can both steer and navigate, and also had inherit the incomplete map from Nami), and Yamato (who is both extremely strong and also knows poneglyph language and mystic arts since Roger or Shimotsuki Ushimaru or whichever Wano expert taught her in the past).
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The only ones left in Onigashima are BM, Kaidou, Luffy. Kaidou questions BM if she wanna die as well since she doesn't leave. BM says she just wants to watch since it's too risky for her to interfere in a battle between two guys that are seemingly dead equal as two WSC's. Kaidou says he recognizes BM's intention to kill whoever is left, and hog the glory for herself. But he cannot simply ignore the ultimate threat that is standing before him, Monkey D. Luffy. The boy already has Poseidon as his ally, Kaidou can't let him take his daughter Yamato just because her capabilities in Poneglyph reading and mystic arts.
During all this time, Luffy just stands perfectly still, his eyes closed and his mind for the billionth time simulating the fusion between Devil Fruit's Neural Awakening and Skysplitter Conqueror's Coat.
The boy opens his eyes, BM floats in the sky with Hera's cloud then she says "Begin."
Both Kaidou and Luffy leap forward meeting at the center, the first clash alone splitting the sky and disintegrate the giant skull at the same time.
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5. No intervention in order to hype up others
Luffy vs WSC Kaidou, is the battle for PK. Just like Zoro vs Mihawk is a battle for WSS. Oda shouldve make it clear to everyone that Luffy vs Kaidou is not a battle they can interfere without their own death as the only result. Make Kaidou oneshot Zunisha as revenge for Zunisha oneshotting Jack, so everyone recognize that Kaidou is an existence with an impossible powerlevel beyond their imaginations. Make Kaidou state "This is first warning, and also the last." or something signifying that he, Kaidou, holds the life and death of the whole alliance, at his mercy.
This will be a solid pay-off to Kaidou's WSC introduction build-up. If Kaidou oneshot a living island then what can they even do lol? Oda should pay his respect to Kaidou this way, not making Kaidou relying on hostage since Oden must be wanked as well lol. Pick your priorities clearly please, Kaidou is a strength-epitome arc boss who btw also decides he wanna be PK. Its an exclusive battle for Luffy. Make it so. As for the others, they can fight BM. Oda can make Orochi as an extremely proficient swordsman who is also a menacing hydra etc, for Zoro to fight against for example. If Zoro absolutely must fulfill dragon-slaying legend as his role, then make Orochi have Seiryu Devil Fruit instead. While Kaidou can be designed to create his own powers with mystic sacrifices or absorbing a hyper mythical artifact or something and assimilated its powers with his own, Original Titan powers or something, something worthy of WSC. Whatever, doesnt even have to be a Devil Fruit in order for Kaidou to achieve his WSC status, Oda can always find another way actually.
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6. Earned powers, Earned Loss
Then after this much preparation and build-up, Luffy can earn his powers, he can battle to his heart's content, THEN he can lose. I agree that Luffy shouldve be beaten in Onigashima battle against Kaidou. But only with point 1-4 fulfilled. Not without. So Luffy' Onigashima defeat shouldve been his first and last, against Kaidou. No fake tension moments, no empty hypes, but an actual WSC and earned powerup, also Luffy becoming the one we actually root for to win an impossible fight, and he lost after all. A whole-hearted defeat that happen even after Luffy prepare himself to the utmost. In exchange, Oda shouldve replaced Kaidou oneshotting Luffy (Udon), with Luffy making strategic retreat instead (see point 1).
7. Finding Out Ways to Heal and Formulate the Final and most original PU, winning the fight by creative perseverance
Luffy can heal himself with meat. Gag moments right? Not for me. Oda shouldve gone all the way and make that stuff a doorway into Luffy figuring out that he can make his rubber body metabolize nutrients extremely fast, converting all of it into protein regeneration and strength-muscle-building or whatever. During that process, Luffy also formulate his last powerup. It can be achieved from figuring out that Ragnarok had CoC infusion. But Luffy doesnt stop there, he acknowledge that just copying his enemy's CoC Coating techniques will not grant him victory since his enemy can also do the same. So Luffy takes a step further, and make something never seen before in this world. It can be Internal Destruction CoC, like Rupture2 powers made entirely from CoC infusion, or it can be compression-based kinetic energy manipulation, or creating an entirely new type of energy that allows him to go massively faster than speed of light (breaking the law of physics in OP world etc erc) whatever, something only someone as creative as Luffy is capable of. So once again, that Luffy' victory and crowning ceremony as the New WSC feels earned.
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