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Confirmed:
Luffy
Shanks
Borderline Confirmed:
Dragon(His father and his son have it, and Doberman said that it shouldn't be a surprise that the son of Dragon has it). Also the leader of one of the most powerful organizations in the world
Imu. Literally worshipped by 5 CoC users + King of the World. Celestial Dragons seem to have lots of CoC users.
Garling. Set up as a major player at God Valley + all the other major fighters at God Valley were CoC users. Father of CoCman Shanks and has enough authority to execute other Celestial Dragons. All the top Celestial Dragons have CoC.
Very Good Chance:
Sakazuki - Previous Fleet Admiral had it, pinnacle of marines in the story.
Kuzan - Had an even clash with CoC user Garp, though no fodders were shown passing out(tbf no fodders were seen passing out from Galaxy Impact either so who knows). Also a Fleet Admiral candidate, but he's much lazier and spent a year drinking after his loss.
Koby - The next "Garp" of the new generation. Set up as the biggest and most important "new" marine. With how inconsistent Oda is with it, Honesty Impact could be CoC.
Sabo - Personally I don't see it but he's Dragon's successor. I think we would have gotten more hints, but he is paralled with Oden so he could have it.
Teach - One of the most ambitious and succesful characters in the story. Chinjao's speech and faith in Teach makes me think he has it. Hasn't shown it yet, but it took awhile for Saturn and Katakuri to show it.
IDK:
Silhouette: Depends who he is. If he's an Elbaf king or important figure I can see it. If he's another Celestial Dragon I also see it.
Buggy - Really depends on how Oda's feeling.