Hancock low diffs. Kuma, who's a fair bit stronger than Hancock, hasn't presented much to place him massively above the Pacifista in terms of anything other than DF hax, whereas Hancock oneshotted several of them easier than Part 2 Sanji and Zoro did. Part 2 Sanji's probably stronger than Invankov as well, considering it's highly plausible he had to face the Okama Queen as the last part of his training.
Hancock turns the Okama to stone, unless Ivankov can use his hormones to make him both sterile and give him an adrenaline rush.