Since the early raws, it was being debated whether Aokiji did use ACoC (we already know Garp has it)? And while it would make sense that Admirals, the strongest fighters of the navy, should also have the strongest powers, this was never specifically shown in the manga. ACoC/Conqueror coating has one consistent visual and that is haki trail on the weapon (sword/fist/club) before the attack which was never shown in the manga for Aokiji.
Secondly the reason for showing Garp and Aokiji training without haki and devil fruit was explicitly done to show that their base physical punching power became equal. And in the final clash Garp is augmenting his power with CoA/ACoC while Aokiji is augmenting his with CoA + DF. Their is a possibility that none of the Admirals the C3 have ACoC and instead make up for it with their OP Logias.
Secondly the reason for showing Garp and Aokiji training without haki and devil fruit was explicitly done to show that their base physical punching power became equal. And in the final clash Garp is augmenting his power with CoA/ACoC while Aokiji is augmenting his with CoA + DF. Their is a possibility that none of the Admirals the C3 have ACoC and instead make up for it with their OP Logias.
