They aren't going to be using gadgets, which was, you know, the whole point of the argument.
What are you talking about? Lure his targets into a trap? How?
They would shake it off pretty quickly, so unless Batman can take out all of them while they're stunned, which is highly unlikely, they're coming after him.
You're really asking how Batman can lure people into traps? He's armed with hIs usual gadgets, (including his utility belt) I'm pretty sure he has many ways to lure them into a trap, especially in this setting.
Let's say he throws his Flashbangs and stuns everyone, he then would have time to flee and hide, with DD being the only one who'd be able to find him, which would allow Batman to deduce that he must have some kind of super-sense to find him because no ordinary human would be able to do so thanks to Batman's specific skillset that isn't rivaled by anyone in this set-up in the stealth department (as far as I'm aware, please correct me if I'm wrong). Thus, if DD does find Batman and Batman assumes he possesses some sort of superhuman ability, it would allow Batman to tactically pick DD apart. If DD "shuts off" his senses like you claim he can, then he'd get the crap beat out of him, because that would be the only thing stopping Batman from
defeating him. If he chooses to use his senses, Batman can use them against him.
It's a win-win for Batman.
But that's ONLY if DD is able to pursue Batman, since he's going to have to fight off some of the other opponents as well, who aren't going to just call a truce to find Batman.
Sure, they may try to flee as well, but they aren't going to be all like: "Hey guys, let's go get that rat-bastard who stunned us! No hitting anyone 'till we beat his ass, okay?"