We've seen this story before. Raiden oneshotting people then getting humbled by technique. Kojiro learning to adapt to any technique. Adam being able to copy any technique. Apollo getting humbled by the tenacity of humans and showing his respect for humanity. And so on.
All the fighters we've seen are melee, and there's only so much you can do—especially when the fight hasn't even utilised the complexity of the map yet. I'd like to see Susanoo be able to split himself into multiple pieces like a Shadow Clone Jutsu, each with different styles, and have this army chase Okita through the buildings... otherwise, it's just another "ooo swords clash together amidst flashbacks" battle and I'd genuinely rather look at femboy fanart of Souji.
Bring in the ranged Hayha or magical Nostradamus already, or the many other historical figures that commenters have suggested.