Ivankov clears the gauntlet.
Ivankov is still significantly stronger than post timeskip sanji, which is clear when we notice the training of the other M3.
Mihawk >Post-ts Zoro
Rayleigh >post-ts Luffy
Ivankov > post-ts Sanji
Im absolutely sure smoker is no problem for invankov, since we have seen vergo destroy him.
Vergo also wouldnt be a problem for ivankov, FBH or not, since we clearly saw him struggling with sanji, who didnt even use haki.
I really dont see Burgess, Luffy, Zoro, or Pica causing Post-TS Ivankov any problems, when ivankov was easily able to hold off Batholomew kuma. And also was able to hold her own against Akainu (Admiral) and Magellan (Admiral Level) and was the only one to ever survive Magellan's poison (excluding luffy who needed ivankov to do it), and toyed with him the entire time.
Honestly, if Law cant beat doflamingo than I definitely cant see how Law can beat Ivankov, when Ivankov and Kuma were thought to be equals, and pre timeskip kuma was thought to be stronger than PRE-TS Doflomingo.
Ivankov should be able to clear this gauntlet.