Black Maria received superior portrayal in the cover page and was the last to go down. She knows Haki, but Oda just doesn’t like drawing it on some characters. Kaido himself has never used Hardening either. Same goes for King, Queen, and Jack
If we're going by the assumption that all the F6 do have haki, she's still portrayed as the weakest offensively to be honest.
-Ulti's headbutts were recognized as strong by Luffy and she even pinned him down to the point he was about to use G4.
-Sasaki's spinning slashes and tackles, as silly as they may be, managed to cut through the Franky Shogun's wapometal.
-WsW has both rokushiki and fully shown CoA coating.
-Page One is the only one who didn't get to show much, but even during his short fight with RS Sanji he was shown to be pretty strong and durable.
Black Maria was swinging a flaming rod around and is now using brass knuckles to punch.
Her presumably being the last one to go down also doesn't matter much considering Raizo vs Fukurokujo is still unresolved and could be the focus of next week's chapter.