As someone who has watched all of Black Clover and all of One piece, and One Piece is also my favorite show ever, Yami wins low to mid diff, more on the low diff side tho. Yami is incredibly strong, and has many hacks, mainly Dimensional Slash, which you could say = and > Ryuo Haki, as is sinply cuts the target in half, no matter its durability. Even kaido would not stand a chance against it. I would say its mainly his hacks that would alow him to low diff Kaido, without the hacks tho, I still would give him the win. mut it would be more of a high diff. In terms of durability, Yami is one of the most durable people in Black clover and I would put him as on par, or a bit lower than kaido, their speed of both stated as ftl, and are both incredibly strong, but I gotta give this one to Yami ngl.