These are basically the characters or versions of Batman related characters who could exist in real life, or at least the most plausible ones... also, these versions are least likely to end up as "worm food". This doesn't include the Nolan Verse, since they are already established as possible.

Thomas Wayne version of Batman - The most likely since, if he were to "properly" deal with Crime in Gotham, he would resort to use of extreme and lethal force. Plus he owns a casino, there are plenty of casino owners in the world, no one would suspect him because he probably wouldn't be much a public figure.

Bruce Wayne(Batman Animated Series, Vol 1-Vol 3.)

This is the PERFECT Bruce Wayne, intelligent, charismatic, slightly-unhinged, stoic, pragmatic, calm, and did I mention that he was intelligent? It's kind of important, he is the World's Greatest Detective, and this incarnation of the character is actually deserving of such a title, because dammit, he sure does live up to it... at least until the New Batman Adventures. Not to mention he wasn't some over-powered ninja god from hell, he was an amazing athlete, but his feats were still plausible and he remained grounded, even when dealing with things like a "Man-Bat". Plus he wasn't so depressing either. One would have to be pretty hopeful to deal with a place like Gotham.

Damian Wayne(666)

Okay, excluding the deal with the devil stuff, this is another Punisher meets Ninja Assassin mixed with a Bat Motif deal, he tries to stray from killing as much as he can, but if forced to, he'll tear you apart without blinking. He's hunted down by the police, and is over-all just an absolute badass, plus, Damian has a love for fighting and violence, so you could expect this guy to be willing to throw down with some of the worst of the worst, not to mention Damian wouldn't mind fighting dirty or resorting to particularly villainous tactics to get the job done.

Bruce Wayne(Batman of Zur-En-Arrh!)

I don't even need to explain myself when it comes to this one, this guy is bat shit insane, it would make sense for him to wear a Bat costume that's multicolored and attack criminals, there have been crazier people in the world. (He's an exception, he could be killed pretty easily, since he's like...off his rocker.)

Then of course the Golden Age Batman....

From what I saw, this guy had no insane abilities, he seemed like a man-hunter of some sort, we know he was an Olympic level athlete, he was a detective and that he was willing to kill. So yeah, thought I'd add him too...

Sidekicks...

Damian Wayne....

He wouldn't really need to be aged up, if he were raised to like the age of 12 to think and act like a proper ninja, then it wouldn't really be a problem so long as he and relied on stealth tactics and weaponry like eskrima, or katanas. I could see this happening, though he'd have to exact exactly like a ninja and use fighting as a last resort, or just simply go predator mode on all those fuckers, so again, emphasis on Stealth Tactics due to his small size... Oh and he wouldn't have a bright yellow cape, he'd have a black one...

Dick Grayson

Secret agent would work just fine, not to mention his regular Nightwing identity could work if he started off as a cop, but was then swayed by Batman's own methods of fighting crime, plus he's an unrivaled acrobat.

Oracle/Barbara Gordon...

She could be a tech support/ hacker type of partner, or just a cop on the Force who's willing to tolerate and allow Batman's assistance.

Birds of Prey

A band of women who fight crime, without larger than life costumes? Yeah, I can see it happening, just remove Hawk, Dove, Poison Ivy, and the Canary cry.

Catwoman

Not really specific, since she is a cat-burglar...

I feel like I've missed a shit ton of characters but I'll update this.....

Year one batman. Besides kicking down a tree and punching a cop through a wall he seemed pretty realistic.

What about lifting a pillar (which took 4-5 men to lift) after he was shot and injured?

@rustyroy: adrenaline or a really strong will, perhaps. I guess that's kind of unrealistic too but I still found year one batman to be pretty realistic relative to other comic versions of batman

What about Earth One?

@rustyroy: that too. I kind of hate that book and try to forget about it but that was probably even more realistic considering batman messed up basic rooftop travel and was pretty grounded, which is likely to happen from time to time in real life.

@jayc1324: it really is my mom told if some idiot decided to jump off a roof like batman he will fall to, nerfed for my taste

robin seems more realistic than batman.

Yeah, Earth One...

@thorson: I'd actually say the oposite. In the real world, how long would a nine year old last against a crap ton of psycopathic criminals? No matter how much training you get from the go@#$mn Batman...

@jayc1324: But he perfected that kick. And I'd mix it in with being a skill feat too. Not to mention he does impressive kicks on a daily basis like oneshotting WW. The guy can lift 1000lbs...And legs are always stronger than the upper body so just imagine the damage he can cause with his lower body.

Terry Mcginnis.

He had character and was exciting to watch.

I was thinking of an older version of Robin.

Christopher Nolan's version of Batman is the most realistic in terms of portrayal and reception to the character in-universe.