Bunshichi, aka "Double Impact Towara", can literally punch a speeding vehicle and knock it over his head. And that's for starters. After it ran him over. And is one of the few people who could give Mitsuomi a good fight. Souichiro nearly split a 16weeler in half with a punch when using the Iron Needle technique. And this is baseline ability.
Aya Natsume has the Ryuugan (Dragon Eyes) and can perceive Past and Future. She effectively has precognition and can perceive things in a 360 degree field, even through obstructions like walls. Yet Souichiro could fight so fast that her Ryuugan could barely keep up with his movements. And that was before he was captured by his father, Souhaku, and made to use his Dragon Fist to consume the abilities of other Red Feather families. Souichiro has over 100 special powers by the end of this.
Among these abilities is using water or even blood as a projectile weapon, making it harder than steel and firing it at super-sonic speeds. He's also acquired the "Dragon Roar", which allows him to control anyone within range of his voice and make them do whatever he commands. Among his other abilities he can open the Dragon Gates inside his power to use various abilities, including the generation and manipulation of lightning.
In Susanoo mode he was effectively a walking god and the only thing that could even really work against him and the absolutely insane amount of ki inside his body, was Maya Natsume's Reverse Dragon Gate which negates all special abilities an diminishes the ki of those around her as she was the Reincarnation of Amaterasu.
At the height of his power as Susanoo, he was effectively unbeatable.
Souichiro can effectively solo this. He can rip you to pieces with just his hair.
He was so tough even before the end, that Mitsuomi had trouble even so much as putting a scratch on him.