I remember people saying that BM couldn't beat the old rayleigh because he was an expert in HAKI, but BM is an expert in the rarest haki, COC, and ACOA.
She doesn't necessarily need a good CoO, her body is made of iron.
And kizaru needed to prepare to capture RAYLEIGH, who used a shit sword, without ADCOC.
I think ODA has already said a lot.