Well I actually meant CotC for Zoro in a way that because his spirit is less strong than Luffy he'll won't be able to knock out 50.000, but maybe half. In that way it isn't something you actively train, but like said rather born with a capacity. Likewise their goals are different; Luffy wants to be Pirate King and Zoro Swordsman king. That doesn't necessiraly mean that Zoro would have a lesser capability per se, but due to the fact that in One Piece Pirate King is the highest attainable rank of infamy. It is logical that it caps with their respective goals. (Just like Gol D. Roger and Rayleigh)
Anyhow, I figured that since Sanji was mostly runnign and fighting Okama and since he is brawler type he'd have to armor his body to stand a chance, even his FLambé attacks hinted to it. With Zoro CoO comes naturally due to hearing the breath of things. Of course when wielding a sword he's probably infusing it with CoA to attest to stronger attacks and slice up more shit.
I forgot about the ranged projectiles infusement works too, and I'd LOVE to see Usopp have BOTH CoA and CoO. I find it hard to imagine his shooting strength tho, since he mostly uses special shots like the pop greens. Not sure where his fighting style ends up tho. (if it stays like the good old 10.000 diff specialized utility attacks, or he also has insanely powerful hitting shots. I mean he has never really hurt some insanely high tier person in most arcs.)
I believe if Chopper wants to keep up his fighting I'd like to see him get CoA, though his different forms solve that partly.
Franky, Robin, Nami and Brook don't need it really for their fighting style. They have very niche capabilities that are extremely good in group battles. Except for Robin and Franky who can dish out some shit 1on1 prty well.
So many possibilities, so little information… xD