The world of One Piece has a very diverse population. The "Wano Country" Arc alone features Giants, Minks, Samurai, Fish-Men, the Longarm Tribe, Humans, and a Lunarian. Though they mostly share a similar appearance, certain races have unique abilities and features. The Lunarians, for instance, have the ability to ignite parts of their bodies. Similarly, the Minks, which make up a good portion of the Straw Hats' allies, have Sulong.
The Minks are anthropomorphic animals mostly living in Zou. Unlike Chopper and the other Zoan Devil Fruit users, the Minks, like the Fish-Men, are naturally half-animals. Even so, they only seem to be fur-covered mammals like rabbits and jaguars. Minks are natural-born warriors with greater physical abilities than ordinary humans and the ability to produce electric shocks from their bodies known as Electro. However, what truly makes them terrifying is the ability they can only use once in a blue moon.
Directly staring into a full moon allows the Minks to use their Sulong forms. The transformation begins with the shrinking of the pupils, followed by their eyes turning blood red. The Minks' fur grows raggedly, especially in the furrier place like the mane and tail, and completely turns white. Finally, their bodies grow in size as Electro constantly surrounds them. It is also said that the Sulong is the Minks' true form.
The Sulong form doesn't just change the Minks' appearance. It also exponentially heightens the Minks' physical abilities, especially the abilities they are already proficient in. For Carrot, that was her jumping capacity and agility. The Sulong form also grants the race enough strength for Dogstorm to refer to it as their race's trump card. Even Pekoms was confident of distracting an entire army of Big Mom Pirates on his own in this form. However, this ability isn't without any drawbacks.
It can only be activated when a Mink stares into the full moon without any obstruction, meaning there's a possibility of failing to activate it despite the presence of a full moon. Mastering it prior to its usage is also paramount due to multiple reasons. An untrained Mink will lose consciousness and immediately go berserk after using Sulong. Sulong also requires a lot of energy, and continuous use of it for an entire night will lead to death. The transformation also isn't instantaneous. There is a window of vulnerability during the transformation, which any smart enemy can exploit.
The wild form first made its appearance during the "Whole Cake Island" Arc. When the Thousand Sunny was surrounded by Big Mom Pirates. Carrot volunteered to single-handedly take them on and proceeded to transform herself into her Sulong form. The empowered rabbit swiftly took care of multiple Big Mom pirate ships and even ripped the helm of Daifuku's ship.
Sulong made a more frequent appearance during the all-out war against the Beast and Big Mom Pirate alliance. Cat Viper and Dogstorm unveil their Sulong forms in their fight against Jack. The Musketeers and Guardians also followed suit and took care of an entire platoon. Meanwhile, Cat Viper and Dogstorm quickly defeated Jack, only failing to finish him due to Kaido's interference.
The Minks' ability to turn Sulong is one of the strongest natural abilities in the world of One Piece. However, this doesn't come without a price. Not only does it require mastery to avoid going berserk, but overusing it may also lead to death, making it a very sharp double-edged sword.