So Big Mom just displayed Shanks' special ability on top of having a devil fruit and better physical strength...
In the moment when Luffy learn all three versions, when Kaido had on his own adv CoC, I kinda know that guys like Garp,Shanks,Mihawk and the others must have something in slave who make them even stronger.
Best example Roger, Whitebeard probablly had adv CoC and adv CoA and his version was in same lvl as Roger, how Roger then match Whitebeard Gura power if his own adv CoC was at same lvl as Whitebeard adv CoC.
I assume like with adv CoA we gonna get two stages of adv CoC, the last stages is probably something like Ashura(because that Kaido call it CoC) with make Garp and coo strong enough to deal with Kaido and the others df powers who also are probably awakenend.
Since Big mom was portrayal Kaido, I assume she has her own "hybrid version" where she fuse with her homies.
Also Big mom not yet use her awakenend power(and based on Bullet we know awakening power from top tiers are insane) so I assume Kaido has his awakenend power too..