Brolong

Justifying with no one asking, I am suspicious now

Isn't that the same martial arts than in the nine cauldrons?

Well pitches are not just numbers. Some pitches are harder to hit even with less speed than others.

Well, the fact is that the sign of being a yonko is to be able to fuse armement haki and conqueror haki, and not just conqueror haki infusion or whatever it was called here. Almost everything here isn't faithful to the original work. You have to read this with other reasons than something that doesn't strays too far from the original.

You are right, Shanks and Yassop are known as observation haki killer for being able to see like 10 and 11 seconds in the future I think.