Torran, you said Halibel "had a thing for children". Can you tell me what you mean by that?
Her Hollow hole is in her uterus, Hollow holes symbolize what they lost, her aspect of death is "Sacrifice", it means she died while giving birth and the pain made her transform into a Hollow. It explains why she went around gathering weaker Hollows and why she calls the Tres Bestias her children, and why she was holding back against Hitsugaya when she could have killed him easily.
This might come in handy. Maybe one in more analysis to come:
All senior captains and Zaraki win. At that point of the story Byakuya was extremely reliant on his Bankai so he would probably lose. He struggled against Zomari with his Shikai and on his fight against Yami he was constantly in Bankai.
Zaraki was fighting against Yami on his rage mode and was pressing him very hard while being significantly injured.
Senior captains are all beasts. Unohana for that matter would probably demolish the entirety of the Espada solo.