One Piece is filled with all kinds of incredible groups, including one that consisted of the brightest minds. MADS was a group of scientists that conducted weapon research and development more than two decades ago. The World Government deemed their discoveries too dangerous, so their entire team was labeled illegal and persecuted. Even though the group disbanded, the members continued their respective projects and continued to produce outstanding results. While the exact number of original members is still uncertain, four of them have made their debut.
Dr. Vegapunk and His Array of Inventions
Even though he's the very first member of MADS known by fans, he is also the only one among the four that is yet to make an official appearance. Dr. Vegapunk is one of the members who failed to avoid the World Government's clutches. When the government absorbed what remained of MADS, Vegapunk became the group's new head. He has since made a slew of discoveries and inventions that aided the Marines on countless occasions, and he's hailed as the greatest scientist in the world of One Piece.
Dr. Vegapunk is the genius behind most of the Marines' high-tech weaponry. However, his greatest creations are the cyborg conversion of Bartholomew Kuma and the Artificial Devil Fruit that Momonosuke consumed. By slowly turning Kuma into a cyborg, Vegapunk was able to mass-produce artificial replicas that are commonly known as Pacifistas. It is rumored that the Artificial Devil Fruit Vegapunk created using the Lineage Factor is a failure, but its effects are visibly better compared to SMILE. After eating said fruit, Momonosuke was granted the same abilities as Kaido's Fish-Fish Fruit, Model: Azure Dragon.
Caesar Clown and His SMILE
Caesar Clown once worked with Vegapunk but got dismissed due to his immoral decisions. Even though he is said to be Vegapunk's rival, he has always been the second-best. When Vegapunk dismissed Caesar for creating a gas weapon for mass murder, Caesar set it off in revolt. This caused a huge explosion that covered the entirety of Punk Hazard in poisonous gas. It's not until a year later that Caesar returned to Punk Hazard to condense the gas and turn it into a sentient being.
While Smiley, the resulting creature of the poisonous gas condensation, is a notable creation, Caesar's scientific genius is better demonstrated through the creation of Artificial Devil Fruits called SMILE. These fruits may be less effective than Vegapunk's, but Caesar has found a way to mass-produce them. This allows Kaido, who held a monopoly over it, to build an army of SMILE users.
Vinsmoke Judge
Vinsmoke Judge is Sanji's father, as well as the king of Germa Kingdom. His primary research interest was the Lineage Factor, which he assiduously studied alongside Vegapunk. He's an ambitious man who doesn't mind sacrificing anything, including his children, to achieve his goal. One of his selfish plans was marrying Sanji to Charlotte Pudding to be part of Big Mom's family.
As a genius geneticist, Judge's best works are his children and the Raid Suits. He has genetically modified his children to turn them into perfect killing machines. This would have included Sanji if not for his mother's intervention. As a result, the Vinsmoke siblings have received superhuman strength and durability, while also having their emotions wiped out. The Raid Suits provide them with enhanced fighting abilities, as well as individualized powers. For example, Sanji's Raid Suit grants him the power of invisibility.
Queen
One of Kaido's All-Stars, Queen is the latest introduced former member of MADS. While it's not known how Queen met Kaido, he was already part of the Beast Pirates during Kaido's arrival at Wano. Just like the other former members, Queen didn't stop pursuing his studies. However, he's the only one that kept all his creations to himself. He's also the current owner of the Ancient Devil Fruit Dragon-Dragon Fruit, Model: Brachiosaurus, which allowed him to transform into a brachiosaurus and a human-brachiosaurus hybrid.
Since Queen's scientific pursuit has never been for other people, his best creation is himself. Similar to Franky, he has augmented his body countless times. He claimed to be a cyborg with numerous deadly armaments and mechanisms. He also managed to replicate every ability Judge's Raid Suits have to offer. According to him, he is already so advanced that even the genius Vegapunk won't be able to replicate him.
The legendary scientific group MADS may have been disbanded by the World Government, but the members never ceased their research. They've proven time and again that they are the brightest minds the series has to offer and their inventions have hugely impacted not only the Straw Hat Pirates' adventure but also the entire world of One Piece.