There are a few essential elements that any proper Batman suit must achieve. Specifically, it needs pointy years, a scalloped cape and a dark color palette. Beyond that, artists and filmmakers are often free to do whatever they want. Keeping that in mind and looking back to George Miller's ill-fated Justice League: Mortal, it sounds like the version of Batman almost played by Armie Hammer would've used one of the most bizarre live-action suits to date. Hammer recently opened up about the suit and explained that it would've taken the form of a fully-functional exoskeleton, saying:
I don't know about you, but I would pay top dollar just to see a picture of what that Batman exoskeleton would look like on the big screen. In typical George Miller fashion, it seems that the outfit would've been incredibly practical and tactical, with many moving parts that Armie Hammer could interact with and utilize. The heavily mechanical aspect seems like the most notable element to focus on, which makes sense when we consider that Miller and Hammer would've needed to convince audiences that this human could stand toe-to-toe with all-powerful beings like Superman and Wonder Woman.
The silver screen Caped Crusader would eventually go on to earn another highly armored suit design on the silver screen, albeit with a different actor under the cowl. Batman V Superman: Dawn of Justice faithfully adapted The Dark Knight Returns exoskeleton used by the billionaire ninja in that landmark story arc. However, the primary difference here is that the Dawn of Justice suit relied heavily on CGI, whereas the Justice League: Mortal suit sounds like it was considerably more practical in its mechanics and functionality.
Of course, while Batman's on-screen costumes have gotten consistently more sophisticated with each passing film -- and they will likely continue to do so going into Justice League -- they still have nothing on what Batman has used in the comics over the years. These have ranged from lighter outfits that offer increased flexibility in hand-to-hand combat situations to suits with heavier armor on the chest to absorb gunfire, to even large mech-suits with red suns built into the gloves to depower Superman if necessary.
In some versions of the comics, Bruce Wayne has even devised a special stealth suit that allows him to hide from any of Clark Kent's various forms of supervision. The point is, the guy loves to diversify his wardrobe, so the Justice League: Mortal suit that Armie Hammer described to Screen Rant isn't terribly surprising. There's an insane well of material for filmmakers to draw from, and it only gets deeper as more stories are written.
While it's a shame that we never got to see Armie Hammer's Batman exoskeleton, we have only just begun to scratch the surface of what Bruce Wayne's outlandish outfits can look like in live action. The character will make his next appearance in the DCEU when Zack Snyder's Justice League debuts in theaters on November 17.