There is Luffy, who thanks to his plot power clowned BM in her own HQ (actually the greatest trouble for the BM pirates when Luffy invaded was not him but BM herself) even if he didn't fight her directly and of course Law and Kidd who beat her finally.
Another one who supposedly could have fought with her and won, or directly shown so much superiority that put a young BM under him without even a fight is of course Xebec.
Maybe she had some clash with WB back in the days like WB did with Roger. Or when Roger stole her poneglyph they actually fought. This explains why only WB was seen by the world on par with Roger and not BM or Kaido. Also when Shanks and BB stole the poneglyphs from Kidd and BB there was a sound beating in the process, could be the same for Roger and BM. But here I'm speculating.
She clashed with Kaido "on panel" at least once for 3 days in Onigashima.
But about mid gen and worst gen guys it seems there is nobody. I doubt somebody will get a "he fought with BM" label at this point. BM, dead or alive, has done her big role in the story, I think at best she will reappear in the final war as a secondary character. So she will just be thrown in that room were past villains are and 99/10p times they are left there to take dust, there would also be no hype to have now somebody to have that feat and also no reason to recall BM (probably some reference in Elbaf but I doubt she will get nore than that).
What I could see is, when the SH get to Elbaf, maybe some strong old giant tried to fight BM to avenge their elders but failed. Dory and Broggy would fit that bill just fine. Then the current king (was he called Loki?) most likely doesn't care since he was ready to sign an alliance with BM in exchange for marrying one of his daughters.
Another one who could have some relation with BM is of course Kuma since Bonney looks a lot like a young BM... But since he is a mindless cyborg who rarely talk we got nothing of it until now.
Most likely some father of the BM family strong enough tried to fight her but for sure it didn't end well. Pound was just too weak while Streusen, who fathers the strongest child/s is just her hidden YC.
