All styles are for drawing references and called something different in universe.
Jiyu-Muay Tai/wing chun
Due to his size and speed, muay tai and wing chun are are ideal for him to learn.
Shitoku- Kung Fu
Shitoku was already extensively trained in hand to hand. But never a specific style to help build focus and balance between them all.
Osata- karate, judo and *numbing kicks(variation of Yugana's Numbing strikes style)
Takaharu- Glima(viking wresting), boxing, and jujitsu
Sanjo- okichitawa/Ojikara(made to disarm and disable opponents quickly) This style is due to Sanjo's dislike of a long fight. *2nd season he creates a zai weapon that utilizes this style a great deal.
Kung fu, Muay Tai, and Boxing are also learned by him.
Ushiku- Boxing and kickboxing at first.
*Master Style(Ojikara he created by fighting so many different styles and taking what he likes. He learned that from Yugana)