I believe Batman has met his match here, and not just against some hyper-powerful opponent. Batman is very, very good at martial arts; but Jack’s better.
Well, Batman has a slight edge at a distance, what with his 'rangs, ropes and darts, but, yeah. This one goes to Jack. Batgirl or Shiva might take him, or Richard Dragon, but Batman would lose a straight-up fight at least 70% of the time.
Batman is smarter than Jack though. He’d “win” by appealing to Jack’s better nature and teaming up, or by doing an end run around him to achieve whatever goal they were fighting over.
Those two would get along famously. They have the same freaking origin, for crying out loud.
Jack! Because he’s cuter.
Especially when his hair is down. swoon
-Anaamika, typical female who’s into these kinds of things.
Jack would thoroughly trounce Batman on their first two or three encounters in heated hand to hand combat before Batman figures out a way to disable him. (Hey, if five Emakandi could do it, Batman can.) Then Aku and his minions would appear to collect Jack and then Batman would suddenly have a change of heart, free Jack and they’d both open up cans of whupass on Aku.
This would be a kickass episode, especially if they could include the Scotsman and Clayface.