The Yonko are the four most notorious and most powerful pirate captains in the world. They are not allies nor are they strictly enemies of one another. Rather, the four prefer to remain autonomous under most circumstances.
These four individually reside within the second half of the Grand Line (known as the "New World"), exerting impressive influence and control over dozens of other pirate crews and self-governing islands. They make up one of The Three Great Powers.
In the decisive Battle of Marineford, Whitebeard, one of the Yonko, met his end towards the climax of the Whitebeard War. Blackbeard, his killer, subsequently usurped his position within the following year. Shanks, another member of the Yonko, arbitrated a ceasefire to end the aforementioned war.
A threat...a demand...when issued by one with absolute, overwhelming power becomes simply inevitable fate...after all, who could possibly oppose it? That is the existence known as the Yonko! And this is what it means to be driven to your very wit's end...!
As an entity, the Yonko are one of the Three Great Powers of the world, with the others being the Shichibukai and the Marines. Their strength and influence are such that they live quite literally as though they are emperors, doing mostly as they please.
Individually, they are considered to be the most powerful pirates in the world, with devastatingly powerful and versatile Devil Fruit abilities, immense physical strength, endurance, and durability, and/or sheer mastery of Haki. Whitebeard, the first Yonko to display his full fighting prowess, was even in his old age considered to be the Strongest Man in the World, possessed the powers of the Gura Gura no Mi, the Devil Fruit considered to be the strongest within that of the Paramecia class, and had mastery of all three types of Haki. He was eventually killed in the Battle of Marineford after receiving nearly 500 grievous wounds, and even then, died standing as a testament to his tenacity and inhuman strength.
Blackbeard, who killed Whitebeard with the aid of his crew, then gained the powers of Whitebeard's fruit through unknown means, thus becoming the first known individual to have acquired multiple Devil Fruit abilities; over the course of the following year, with the aid of his newfound powers, he would usurp Whitebeard's former position as a Yonko. Kaido and Big Mom have been noted for their bodies being impervious to wounds and conventional weaponry.
Though powerful in their own right, much of the Yonko's martial strength can be attributed to their elite and abundant crews, as well as to their close alliances with other pirate captains. After the timeskip Trafalgar Law cited that there are only two methods of surviving in the New World, and that is to be protected under the umbrella of a Yonko's dominion and become their subordinate or to constantly oppose their authority. At least Teach and Kaido are both gaining influence and strength in the form of amassing Devil Fruit powers, both in their own unorthodox methods. Big Mom intends to increase her crew's power by forming an alliance with the legendary Germa 66 and gain access to their advanced technology.
Whitebeard's crew amounted to over 1600 men and he also had 43 subordinate New World pirate crews to aid him in his efforts to rescue Ace, each headed by an infamous pirate captain. Some of these subordinate captains were very powerful in their own right, as seen with Little Oars Jr.'s impact as a key player for the Whitebeard Pirates during the Battle of Marineford, and who required the efforts of three Shichibukai to be brought down.
Due to the sheer size of their crews, most of the Yonko utilize several elite commanders to lead their forces; Whitebeard originally had sixteen division commanders (each leading 100 men), Kaido has his three Disasters, Big Mom has her Three Sweet Commanders (originally Four), and Blackbeard, who originally only had a small crew of under ten men prior to his becoming a Yonko and expanding his crew size drastically, later has it subdivided through his Ten Titanic Captains, some of whom were members of his original crew. As seen with top Whitebeard commanders' Marco, Ace, Jozu, and Vista's skirmishes with the Shichibukai and Marine Admirals during the Battle of Marineford, these top officers are seen to be able to contend with the elites of the other two Great Powers.
Due to their exposure and feats as executive officers for the Yonko, the commanders are regarded as a huge threat by the Marines, second only to their Yonko captains. Thus far, the four highest known active bounties all belong to Yonko commanders (Cracker, Smoothie, and Katakuri of the Big Mom Pirates at 860,000,000, 932,000,000 and 1,057,000,000 respectively, and Jack of the Beasts Pirates at 1,000,000,000). Interestingly, none of the Yonko other than Big Mom in her youth (at least 40 or more years ago) have had their bounties revealed.
Accordingly, they each have a large territory that they govern within the New World. The Yonko provide protection to all who reside within their territories, keeping the borders safe from any faction that may wish to invade them. Big Mom's territory, Totto Land, is heavily protected by scouting ships and by watchtowers called Tartes that dot the coastlines of each of her islands, both prepared to inspect and potentially shoot down any ships not affiliated with her crew. She also has territorial sea slugs that patrol the waters, warning would-be intruders that they are entering her territory. Finally, Big Mom has 34 ministers as part of her administration, one to run the affairs of each of her territory's subsidiary islands.
Because of their power, the Yonko can declare chosen locations as their own. The mere declaration is often enough to compel others, both Marines and pirates alike, to acknowledge and respect the Yonko's authority. When Whitebeard declared the crime-ridden Fishman Island to be under his control, he immediately ended all pirate attacks on the island as well as its slave trade.
They can also motivate others to partake in a life of piracy. Shanks personally inspired Luffy, and Whitebeard's last words inspired many pirates to travel to the Grand Line.
It is only with the combined efforts of the Marines and the Shichibukai, as well as the distrust amongst themselves, that keeps their power in check. During the Battle of Marineford, the Marines and Shichibukai needed to fight together just to engage one of the Yonko, Whitebeard, his crew, and their allies. The arrival of a second Yonko, Shanks, and his crew, immediately brought an end to the hostilities, showing the power and influence they have without even needing to resort to combat.
The Yonko themselves are not a coalition like the Shichibukai, and they follow their own discrete agendas. Nevertheless, some of the Yonko like Marshall D. Teach and Charlotte Linlin still have the intention of locating the One Piece and becoming Pirate King, while former Yonko Whitebeard had no such interest in doing so.
The possibility of two or more of the Yonko forming an alliance was enough of a threat to cause the World Government to panic, as seen when it unsuccessfully attempted to prevent a meeting between Shanks and Whitebeard. The World Government feared that the two Yonko would unify, creating a much more imposing threat that would disrupt the balance between the Great Powers. A war between two of the Yonko is considered a terrifying crisis, as Shanks' interception of Kaido's advancement on Whitebeard had taken the Marines by shock and awe, putting the World Government in a "cold sweat" as stated by one of the Marines.
Though very powerful, they do have potential threats from even lower ranked fighters and pirates. For example, it is said that once Elizabello II has gathered enough strength, his King Punch can knock down even a Yonko. They also have a number of connections that link them to various members of the Worst Generation, be it on friendly terms like Monkey D. Luffy and Shanks or allies like Capone Bege and Charlotte Linlin were.
However, because of their immense power, it is necessary for factions aiming to oppose them to first form an alliance with other factions in order to bring the Yonko down. However, even with pirate crews forming multiple alliances, the chances of defeating a Yonko are still extremely low. When the Straw Hat Pirates and the Heart Pirates formed an alliance to defeat Kaido, Law informed Luffy that he believed their chance of success was still only 30%.
It's unknown how long the title of Yonko has existed or how it was created. However, all known members, past and present, have been active pirates for at least the past twenty seven years, as Shanks (the youngest of the Yonko) was was seen during the Edd War as a part of Gol D. Roger's crew.
Whitebeard was active on the seas during Gol D. Roger's voyage across the Grand Line; he was said to be one of the few people who could rival Roger, as well as the man closest to One Piece after Roger's death. However, he had no intention of finding the treasure.
Big Mom was also on the seas during Roger's voyage and even encountered him when he managed to acquire and read her Poneglyphs, allowing Roger to beat her to Raftel.
Throughout his life, Kaido was defeated seven times by the Marines and other Yonko. However, all of their attempts to execute him were unsuccessful.
Some of the Shichibukai have fought the Yonko in the past; Shanks and Dracule Mihawk frequently dueled in their younger days, Gekko Moriah fought Kaido, and Crocodile fought Whitebeard.
Twelve years ago, Shanks visited Luffy'shometown. It is unknown if the title of Yonko existed at that point in time or if he was one at the time as well.
About four years ago, Kaido formed a partnership with Donquixote Doflamingo and Caesar Clown so that the two would give him Artificial Devil Fruits known as SMILEs, which he used to create an army of Devil Fruit users known as Gifters.
All of the Yonko seem to have strong fleets, including huge ships and elite crewmen. At some point, they all traveled to the New World where they are currently locked in a stalemate, unable to progress any further into the Grand Line. This is a product of the combined efforts of the Marines and the Shichibukai, as well as the presence of the other Yonko. A particular reason for their inability to reach Raftel is the fact that one needs all four Road Poneglyphs to determine its location; one is possessed by Kaido, one possessed by Big Mom, one is located on Zou, guarded by the Mink Tribe and the last one is in an unknown location.
The World Government allowed the world powers to stay as they were for a long period of time. With the Yonko stuck in a deadlock, the world remained stable. However, after the defeat of Crocodile by the Straw Hat Pirates, the World Government was alarmed to learn of two of the Yonko, Shanks and Whitebeard, arranging to meet each other.
On top of the destruction of Enies Lobby, the Marines experienced another defeat in the New World when a blockade failed to prevent Shanks and Whitebeard from making contact. Fearing the two crews might form an alliance, the World Government anxiously waited to know the outcome.
During the meeting, Shanks's presence upon boarding Whitedbeard's ship caused a majority of the crew to collapse. Shanks shared sake from his hometown with Whitebeard as a token of friendship while at the same time issuing a grave warning.
Shanks told Whitebeard that his days as the strongest pirate were coming to an end, warning him of the new era that was to come. With Blackbeard making his move toward prominence, he would depose Whitebeard from his throne. Shanks also tried to convince Whitebeard to call the 2nd Division Commander, Portgas D. Ace, back from his pursuit of Blackbeard. Whitebeard stubbornly refused Shanks's warning, and the two clashed. The sky seemingly split in half when their weapons collided, much to the horror of the members of both crews.
In an attempt to rescue Portgas D. Ace from execution, Whitebeard summoned all of his allies from the New World in preparation for war. Kaido attempted to attack Whitebeard, but he was intercepted by Shanks.
Whitebeard and his crew and allies arrived at Marineford three hours before Ace's scheduled execution and initiated what would be known as the greatest war since the beginning of the Golden Age of Pirates. During this battle against the Marines, Whitebeard revealed how debilitated he had become over the last two decades, and he steadily acquired increasingly critical wounds from his enemies because of his weakened state.
During the battle, he destroyed most of Marine Headquarters, easily defeated two large giants who were at the rank of vice-admirals, and withstood the combined efforts of the three Admirals. He was able to help free Ace, but Admiral Akainu executed Ace afterwards. An enraged Whitebeard dealt a serious blow to the admiral, but it was not enough to completely incapacitate him.
Remaining at Marineford alone to resolve the conflict with the Marines, Whitebeard was attacked and ultimately killed by the Blackbeard Pirates. Shortly afterwards, Shanks arrived at Marineford with his crew. His presence spared the remaining allies of Whitebeard and brought the war to an end. Shanks challenged Blackbeard, which the latter turned down before leaving with his own crew.
According to Eustass Kid, Whitebeard's death and resulting vacancy among the Yonko caused the balance of the Three Great Powers to collapse, leading to chaos around the world. Islands that were once under Whitebeard's protection, such as Foodvalten, came under attack by pirates.
Teach also usurped Whitebeard's position as the fourth Yonko as the Gorosei predicted, having managed to conquer most of Whitebeard's former territory and becoming stronger by hunting down powerful Devil Fruit users and taking their abilities after killing them. He became recognized as a Yonko after overwhelmingly defeating Marco and the remaining Whitebeard Pirates a year after the Summit War in the "Payback War".
When the candy factory was demolished during the uprising of the New Fishman Pirates and Flying Pirates, Fishman Island almost provoked Big Mom's wrath, since the island did not have enough candy for the tribute to her. Monkey D. Luffy pledged that he will claim Fishman Island as his protectorate by defeating Big Mom, shifting her fury from the island to himself.
Teach was heard talking with Jesus Burgess via Den Den Mushi, with Burgess stating that Kuzan could not be trusted. Hearing that Luffy had arrived, Blackbeard greeted the young pirate and expressed surprise that he was also a combatant in the Corrida Colosseum tournament for the Mera Mera no Mi. Knowing why Luffy entered the tournament, Teach assured him that Burgess would be the combatant to obtain the fruit and that it would be the same as having Ace join his crew, since Ace had rejected his previous offer. Luffy then angrily stated that he would never allow him to steal Ace's power.
Kaido went up to Ballon Terminal, where he encountered Urouge, who learned of his intention to commit suicide and let him proceed. After jumping 10,000 meters below on the Kid Pirates' base, he came out of the hole unharmed and faced the Supernovas Eustass Kid, Scratchmen Apoo, and Basil Hawkins. He yelled for Doflamingo to make preparations for battle and promised to start a massive war since he became bored with the world. Kaido defeated Kid during their confrontation and made an alliance with Apoo; the fate of Hawkins and the rest of the three crews remains unknown.
Kaido became very unhappy upon finding out about Doflamingo's defeat and Jack's failure to rescue him, drowning his sorrows in alcohol as he grieved that he could no longer get SMILEs to make more Gifters and create a crew entirely composed of Devil Fruit users. His subordinates wondered what they should do about Monkey D. Luffy and Trafalgar Law, the ones who had defeated Doflamingo, but Kaido entered a drunken rage upon hearing their concern, pointing to the defeated Kid to show the vast power disparity between him and the Supernovas.
According to a newspaper report, Blackbeard led an attack on the Revolutionary Army's base on Baltigo, destroying it by the time the Marines and Cipher Pol arrived. The Blackbeard Pirates fled after briefly clashing with Cipher Pol.
Three days before the Tea Party, Big Mom oversaw the wedding preparations. As she sang and danced with her underlings, she looked forward to the wedding and stated that she heard of Luffy's presence in her territory.
Later, Big Mom developed an intense craving for croquembouche and went on a rampage through Sweet City, eating everything in her path and even killing one of her sons, Charlotte Moscato, when he got in the way. She was then stopped by Jinbe, who fed her some croquembouche tourists. Jinbe requested to leave Big Mom's crew, and Big Mom seemingly agreed, but stated that he had to lose something in return.
After learning of Cracker's defeat, Big Mom had Zeus and Prometheus generate a massive storm and dispatched an army to deal with Luffy. After the Vinsmoke Family arrived at her castle, Big Mom welcomed them and had lunch with the Vinsmokes and Pudding. Sometime after the lunch meeting, Big Mom seemingly accepted Sanji's request of sparing his friends in exchange for him not running away.
Later, Big Mom gave the Vinsmokes a tour of her library. After being informed that Luffy and Nami had been captured, Big Mom spoke to them via Den Den Mushi and revealed her hatred for Lola for running away from an important political marriage. Once she heard about an intruder at the Room of Treasure, she immediately went there and encountered Brook.
After overpowering Brook, Big Mom then decided to keep Brook as part of her collection. She and Pudding then spoke in private in the Queen's Chambers, where they discussed and went over their plan to assassinate the Vinsmoke Family. Soon afterwards, Big Mom went to bed and fell asleep with Brook in her arms. After several failed attempts, Brook's comrades managed to retrieve Brook and replaced him with a skeletal lookalike.
After waking up the next morning, Big Mom cried in grief when she thought Brook died, but cheered up when reminded about the wedding cake. When the guests arrived and the tea party began, Big Mom arrived at the venue and greeted them. During the tea party, Big Mom was presented with Mother Carmel's portrait before the wedding guests presented their gifts. The Tamatebako was also brought to the venue and Big Mom planned to open it after the wedding.
The wedding commenced when Sanji and Pudding entered the venue and Streusen presented the wedding cake with the altar at the top. When the exchange of vows began, Big Mom's plan went awry when Pudding did not carry out her task after Sanji called her third eye beautiful. After Katakuri's attempt on Sanji's life failed, several duplicates of Luffy burst out of the wedding cake, ruining it in the process.
As chaos ensued at the wedding venue, Katakuri thwarted Luffy's attempt to destroy Carmel's portrait. Jinbe then appeared and freed Luffy from Katakuri's grasp before officially declaring that he was leaving the Big Mom Pirates in order to join Luffy's crew. In response, Big Mom attempted to take away Jinbe's lifespan, but her power had no effect on him because Jinbe showed no fear towards her. While Big Mom was distracted, Brook smashed Carmel's portrait. Big Mom was deeply shocked at Brook's actions, but she did not scream due to being torn over both the loss of the portrait and her wedding cake.
When Luffy then showed Carmel's broken portrait to Big Mom again, Big Mom started to cry and let out a huge scream while releasing her Haoshoku Haki, causing several guests to faint and others to become immobilized by the sound. She then fell to her knees and scraped them just like before. Taking advantage of her vulnerability, Bege, Vito, and Gotty fired their KX Launchers at her in an attempt to assassinate her. However, Big Mom's scream detonated the rockets before they could reach her. When Caesar flew into the venue with the escape mirror, Big Mom's scream shattered the mirror as well, leaving Bege and Luffy's groups trapped in the venue.
Bege transformed into a fortress and his allies and the Vinsmoke Family ran into it to take shelter. Big Mom later returned to her senses and began attacking the fortress, injuring Bege in the process. Bege later tried to escape by turning back into human form and having Caesar fly him out while Luffy, Sanji, and the Vinsmoke Family engage Big Mom in combat.
During the confrontation, Luffy activated Gear Fourth and briefly clashed with Big Mom before falling back. Judge then charged at her, condemning the Yonko for crushing his dreams. In response, Big Mom shattered his spear and struck him down with a thunderbolt from Zeus. Judge's sons, Niji and Yonji, raced to attack Big Mom, but she quickly and easily defeated them as well. After her children overwhelmed the rest of her enemies, Big Mom prepared to execute them. However, the Tamatebako fell to the foot of the Chateau and exploded, toppling Big Mom's castle.
Big Mom then fell along with her castle while her enemies escaped. However, the Big Mom Pirates were saved when Streusen used his ability to turn the castle into soft cake. To her children's horror, Big Mom began suffering a craving illness for wedding cake. During her rampage, she killed Opera. Before she could cause any further damage, Perospero tricked her into going after the Straw Hats.
Big Mom then relentlessly pursued the Straw Hats while riding on Zeus. Along the way, Nami managed to slow Big Mom down by causing Zeus to drop her. Big Mom's crew caught up to her and joined the pursuit, but Nami used Zeus to strike Big Mom and her nearby crewmates with a massive thunderbolt. However, Big Mom withstood the attack and continued pursuing the Straw Hats. She followed them back to their ship, but the Straw Hats successfully escaped her grasp with a Coup de Burst.
However, Linlin continued her pursuit with Perospero's help. In her madness, she created a wave homie and attempted to drown the crew, but the Straw Hats managed to escape again thanks to Jinbe's skill as a helmsman. Perospero soon learned about their survival as well as about their rendezvous at Cacao Island. He attempted to steer Big Mom there, but unfortunately Linlin turned her attention towards Nuts Island. Linlin then rampaged on Nuts Island, demolishing many buildings. Once she spotted Luffy, she pursued him until he escaped into the Mirro-World.