Captain Johannes “Steelbeard” Stalskegg the Perrzerker of the Stormraider Pirate Crew; He is known as one of the oldest and saltiest Pokemon Pirates still flying the black flags. Legends of his exploits tell that wherever he sails, he brings dark thunderstorms with him.

Vikings were a kind of Pirate from Scandinavia who raided and settled many parts of northwestern europe between 793 and 1066, a good almost 600 years before the Pirate Golden Age. Perrzerker is specifically a Viking Berserker; devotees of Odin who would wear an animal pelt and go into a trance-like fury which we believed was caused by them consuming hallucinogenic plants or mushrooms prior to battle so they couldn't feel pain and would then attack their enemies with reckless abandon.

I also based his outfit design off of the historical Edward Teach aka Blackbeard, as opposed to Ratbeard who is inspired off of the One Piece version of Blackbeard, although Ratbeard doesn't actually have a real beard and Steelbeard's Beard is a metallic white not Black... Since they are a Rat and a Cat I like to imagine the two of them are Fierce hated Rivals!
The historical Blackbeard actually didn't like hurting innocent people so he put on a terrifying theatrical performance and would light fuses in his beard, so he could get by with the reputation of being the the most infamous Pirate in the world without needing to actually hurt people. He also wasn't exactly a true abolitionist, but he liberated many Slave Ships and many of those freed slaves then joined his crew and he notably cared a great deal about his crew.