Beasts Pirates

The Hundred Beasts Pirates are a pirate crew ruling in the New World, led by the Yonko Kaido.

Past
At some point in the past, Kaido formed the Hundred Beasts Pirates. Sometime during the last twelve years; Kaido and his crew defeated Moriah and his crew.

Sometime within the last four years, they formed an alliance with Donquixote Doflamingo and Caesar Clown in order to gain an army of artificial Zoan Devil Fruit users.

Marineford Arc
Upon hearing that the Whitebeard Pirates were headed to Marineford, the Hundred Beasts Pirates tried to intercept them so their captain could kill Whitebeard. However, they were stopped by the Red Hair Pirates.

Dressrosa Arc
Led by Jack of the three Disasters, several of the Hundred Beasts Pirates entered Zou to search for Raizo the ninja. They came into conflict with the Mink Tribe, who easily beat back the Pleasures, leading Jack to send in the Gifters. Jack and the Gifters then came into conflict with the Musketeers led by Inuarashi. However, when the sun set, the Musketeers were forced to retreat and the Guardians took over. Their leader, Nekomamushi, dealt a large blow to Jack, and the minks held the advantage. However, Jack used Caesar's poison gas weapon to overwhelm the minks and destroy the Mokomo Dukedom, sending Duke Inuarashi into a coma.

The search continued for several days as the Straw Hat Pirates led by Sanji entered the island and came into conflict with the Hundred Beasts Pirates. The Straw Hats managed to defeat Sheepshead, the leader of the Gifters, and the pirates following Sheepshead retreated. It is unknown what became of them, though it was hinted that the Straw Hats warded them off.

While this happened, other members of the Hundred Beasts Pirates received word that Donquixote Doflamingo had fallen. Meanwhile, Kaido attempted suicide by jumping off a Sky Island and landed on the Kid Pirates base. He survived the fall and prepared to have Doflamingo help him start the greatest war in the world.

Jack left Zou to go rescue Doflamingo from incarceration and attacked the Marine convoy that was escorting him. Though he succeeded in sinking two of the ships, Jack was eventually brought down and reported as dead, though his body was not found.

Jolly Roger
The crew's Jolly Roger is a skull with a bone in the middle of a pair of crossbones. The skull has horns similar to Kaido's.

Organization
Kaido, the captain, has full control over the crew. At his side are three beings known as the Disasters (災害). One of them, Jack, has the ability to become a mammoth, granting him immense size and strength. Jack has authority over the Gifters and Pleasures. The crew also has X Drake, another ancient Zoan-type user like Jack and a member of the Worst Generation.

One division of the Hundred Beasts Pirates is called the Gifters (ギフターズ), a group lead by the Headliner Sheepshead. All the Gifters have a pair of black horns. They appear to have Devil Fruits of a Zoan-type nature, but unlike normal Zoans, they can transform their arms into different parts of the animal's body.

Another division is the Pleasures (プレジャーズ), who resemble foot soldiers and do not appear to have any animal traits. They each wear a hat with one horn, and smile no matter how appropriate the circumstance, even when taking damage.

Crew Strength
The Hundred Beasts Pirates are led by the Yonko Kaido, making them one of the four most powerful pirate crews in the world. Donquixote Doflamingo, a former Shichibukai and the leader of an incredibly powerful pirate crew of his own, who usually maintains a fearless attitude was deeply scared of Kaido. Kaido also defeated another Shichibukai, Gekko Moriah, and massacred his crew. They attacked the Whitebeard Pirates in the hope of killing Whitebeard, something few would dare, and took on the Red Hair Pirates. They were stated by the Gorosei to be one of the few entities capable of stopping Blackbeard and his crew. During the timeskip, they formed an alliance with the Drake Pirates, a crew from the Worst Generation.

Like the other Yonko, the Hundred Beasts Pirates possess territory in the New World, and they have been shown to rule with an iron fist and put a stop to any insurrection.

The true strength of this crew lies in their Underworld connections. Due to Kaido's alliance with Donquixote Doflamingo and Caesar Clown, they had access to SMILEs to help form an army of over 500 artificial Zoan Devil Fruit users. They also have access to Caesar's poison gas weapons, which they used to destroy a city of minks.

Translation and Dub Issues
The crew's name, Hyakujū Kaizokudan (百獣海賊団), literally translates to something along the lines of "Many Beasts Pirates", "All Beasts Pirates", or "Hundreds of Beasts Pirates".

The term "Hyakuju", meaning many or all beasts, is a compound word that combines the characters for Hundred (百) and Beast (獣). It is seldom used and most often found within the Japanese idiom Hyakujū no Ō (百獣の王), or "King of Beasts" in English, consequently causing confusion amongst One Piece translators on how to render the term.

Additionally, Viz decided to take the translation into a whole new direction by opting to use the title "Animal Kingdom Pirates".

Trivia

 * The crew seems to have a card games theme with Sheepshead and Ginrummy. Jack and Scotch are references to Blackjack (or simply the Jack playing card rank) and Catch the Ten (also known as "Scotch Whist") respectively.
 * This is the fourth card-themed crew after Spade Pirates, Donquixote Pirates and the non-canon Trump Siblings.