Now Ushimaru is stronger than Zoro?
There's no doubt in my mind he was a strong samurai. But there's nothing to support him being stronger than Zoro. Let me know when he can scar Kaido. Nerfed and weaken Zoro, with 20 to 30 broken bones, bested and scarred Kaido.
I do see Ushimaru being stronger than Katakuri.