Three scenarios, arena rules, standard gear (batarangs, ropes, smoke bombs, armor, etc). The arena is the sewer where Bane defeated Bat-Bale. The Batmen can escape through the tunnel/water slide like Gordon did, but then that would be a ring out and counts against them (no more Batmen = automatic win for Bane).
1. One-on-One: Bane fights each Batman separately, fully refreshed for each fight. Who does he beat in a one-on-one match? Who beats him?
2. Mini-Gauntlet: Bane takes on, in order: Clooney, Kilmer, and Keaton. No rest. The instant that one Batman is KO'd/broken/killed, the next Batman drops in. Does Bane make it through?
3. All-Out Battle: Bane engages all three Batmen simultaneously. Can he beat them all?