Cass. They've actually sparred multiple times, and it looked to me like Cassandra had the small edge (the first time he thought he was winning... til he coughed up blood, he literally didn't notice the damage she was doing. The second time they were fairly even but he was retreating constantly).
Also, she's beaten Shiva without outside aid twice to his zero. She does better against Slade than him.
I mean, end of the day, Cassandra was top of the heap all the way to the reboot. Not by a lot, but she has the best showings.
Originally posted by BruceSkywalker
Batman already knows her weaknesses,,
And vice-versa. This isn't him with his gadgets or such, this is martial arts without tools to speak of (aside from using cloth from the gi, which is something Cassandra'd take into account).
Overall you could argue Batman, but this is martial arts, and the feats are where they are.
Cass has stalemated Slade. But Batman despite losing to Slade has actually defeated him. So they both have different advantage points there.
In there sparring matches Batman did well the first time and the other good one she made him cough blood but IIRC Bruce had asked her to quit hold back or something or that she is not doing all she could. The fight when they were both sort of mentally unstable it depicted them as equals. With her having more offense fighting and Bruce more defensive fighting.
Cass has done better against Shiva but it can be argued that Batman vs Shiva match ups there were always "interfered" or outside factors as Shiva has never defeated Bruce straight up.
In a pure martial art fight point match, I would give it to Cass but in a street fight it could go either way.