In the dystopian future of Son of Superman, the 1999 graphic novel by Howard Chaykin, David Tischman and J.H. Williams III (which was just recently reprinted in a DC Comics Presents edition, and even more recently discussed by me here), Superman has gone missing, and the remaining six member of the Justice League have gradually been corrupted in their efforts to maintain the status quo.
This alternate, future version of the League serve as the antagonists of the series, with various members exhibiting various degrees of culpability for the negative state of the Superman-less world. The most obvious change between this ineffective, conservative League and the "real" Justice League of 1999 was visual. Artist Williams gave the team new costumes that were personalized versions of the same basic black costume, with chest-icons and colored stripes terminating in arrows.
"Costume" perhaps isn't the best word though. I suppose "uniform" is more fitting, as this League is a team on which the various members wear clothing that resembles that of the others. Not unlike a sports team, only instead of the names on the back of the jerseys differing, they retain their icons and most iconic costume elements (Batman keeps his cape, Wonder Woman her bracelets, etc.)
This wasn't the first time a super-team was outfitted with a sports-team like uniform. Certainly the X-Men have gone through several iterations where the characters wore matching costumes, certainly in their first appearance and the First Class era. The cartoon series X-Men: Evolution similarly gave the X-people matching but individualized costumes. During the second half or so of 1993-1996 series Justice League Task Force, Martian Manhunter J'onn J'onnz outfitted his team of trainees with matching uniforms. I believe The Avengers went through a period where they wore matching jackets too.
Because of my interest in superhero costume design, I actually really like the idea of a team with matching costumes, if only to see what artist might come up with to unify disparate costumes worn by different characters created by many different artists over the years, although it's often difficult to imagine an in-story reason why a team of individuals like, say, The Avengers or Justice League might actually don them.
A one-off Elseworlds book like this is a neat opportunity to costume the Justice League in matching outfits, as it helps differentiate them from the real, regular version of the characters, and the change need not stick around very long.
Here's what Williams came up with:That's Green Lantern Kyle Rayner and Flash Wally West; their costumes are fairly identical, save for a few signifiers, like Kyle's ring and Flash's little Mercury-like wings on his mask.
This League's Aquaman is a much greater departure than either its Flash or Green Lantern:Most obviously perhaps (at the time, anyway) was that he was once again clean-cut looking, with short hair and no beard (Remember, the Aquaman of 1999 looked like this). He retains a bit of the fishs-cale/chain-mail material that the classic Aquaman's shirt, and the '90s's Aquaman's pants, had, but now it is blue instead of orange or green (save for in one panel, where it was colored orange). His color is neither orange nor green, but a light blue, which matches his new symbol, a simplified wave design instead of the traditional golden A.
Also worth noting is his hand. This Aquaman has a futuristic-looking prosthetic, like the kind he adopted a few years after he took to wearing a harpoon on his hand, but Williams has it on his right hand; Aquaman lost his left one.
J'onn J'onnz had one of the more dramatic redesigns. His costume is much more conservative, showing relatively little green flesh, at least compared to the shorts, harness, boots and cape combo he usually wears. It does still have short sleeves though, to show off his arms. (J'onn looks good in short sleeves). Interesting choice with the chest icon, too—J'onn is the one who gets to use blue and red (Wonder Woman and Superman both wear white instead), and he gets a big "M" for a symbol, instead of an X to echo his harness, or the astrological symbol for Mars, or a red planetoid to represent Mars.
The most dramatic redesign is Batman's: How strange Batman looks without his cowl...I think his cowl, with its white-triangle eyes, pointy nose and, especially, pointy-bat ears may be his main visual signifier, even more important than the scalloped batwing-like cape or Bat-symbol on his chest.
Interestingly, his secret identity is still secret at this point, despite the smaller mask that reveals his hair and more of his face. At the risk of spoiling something form a 12-year-old story, I'll note that once Superman does return and comes into conflict with the League, Batman leaves their ranks to ally himself with Superman, and he does so wearing a costume more closely resembling his original one, with the Bat-cowl, scalloped-gloves and a Bat-symbol without a yellow arrow attached.
Here's what Superman dons when he rejoins the new League: Little more than the color-scheme has actually changed. He lost the trunks and belt, and the sleeves extend all the way over his hands to form gloves, but otherwise it is his originally costume (It looks incredibly similar to the costume that an evil version of Superman from the Justice League cartoon would wear in a 2003 episode featuring the fascist "Justice Lords")
Finally, here's Wonder Woman's costume: The main thing differentiating her black body stocking from that of the boys is the presence of her bracelets (here white to match her color scheme) and the lasso on her side.
I actually like this one a whole lot, as it contains the most basic Wonder Woman signifiers while remaining completely different from he regular costume.
It occurred to me while looking at this that it would actually make a really great costume for Donna Troy to wear in the DCU. The costume she's been wearing for the last decade or so, which shares the same black and white color scheme and certain elements (bracelets, white boots) suffers from its plunging neckline and lack of sleeves, which some artists use to as an excuse to plunge her neckline so deep it becomes a bellyline. Troy's costume also suffers from the star-spangle effect; its supposed to resemble the night sky, but because of computer coloring, it generally just looks like a cheap special effect that projected onto a black jumpsuit.
Later in the book, either due to coloring, or simply Williams drawing it differently in close-up than he did in medium or longshots, it appeared as if Wonder Woman wasn't wearing a single body-stocking type of garment, but actually had a pair of tights on under it, of a slightly different shade of black. That works too.