I group Cipher Pol 0 with CP9; which is to say pre timeskip levels of strength, given how CP9 was touted as the best. If I recall, they needed all three admirals, dozens of vice admerals, and around 5 warlords to fend off one emperor's crew + allies, so I rate their strength lower, but we never got a clear read on the combined strength of Whitebeard's buddies. The WG leaders and their hidden muscle (not the navy) could still be scary, I suppose, but we saw Fujitora get boxed into the ground by a half dead Newgate, so I'd put admirals well below Yonkais.

All that to say, once Strat Hats can beat Big Mom and/or Kaido, not much can touch them in a fair fight.