Feminists have long been critical of how female superheroes are presented in comics. In terms of appearance, they have expressed concerns about the body types of female heroes, the way they are posed, and the skimpy costumes most wear. One interesting visual response is the Hawkeye Initiative in which Hawkeye (or another male superhero) is drawn in the same pose and costume type as a female superhero. As would be imagined, the male hero looks absurd when so posed and costumed, which is exactly the point.
While the presentation of female superheroes in comics is certainly a first world problem, it does raise some important concerns. These concerns normally focus on such matters as the impact on body image, but my interest here is with considering the superhero costume from a practical standpoint. That is, what such costumes should be like when considered from a realistic perspective. While I am no expert on fashion, I will draw on my experiences as an athlete, martial artist and gamer to guide the discussion.
In the realm of fiction, being a superhero generally means being very physically active (running, swimming or flying after villains) and engaging in combat. This means that a sensible superhero would have a costume designed to take these into account.
While I am not a superhero, decades of competitive running have given me considerable insight into what sort of clothes are best to wear. One important factor is mobility—you need to be able to move properly in athletic clothing. One approach is looser fitting clothing that allows a lot of motion (such as running shorts) while another is the tight-fitting spandex (such as running tights) that also allow free motion. As such, the idea of heroes wearing tights makes sense—for the same reason that it makes sense for runners to wear them. Another important factor is temperature management. If a hero is like a normal human, they will generate body heat and sweat when they are active. As such, they will need to be able to stay cool while active but also remain warm when they are just patrolling or engaging in dramatic dialogue.
As a runner, I wear as little as possible when I am running in warm weather (for me, “warm” is anything over 55 degrees). This typically means just shorts, socks and shoes. Many other runners are the same, with women generally adding at least the legally necessary coverage. Presumably a superhero that runs about would also want to wear as little as possible. As such, in warm weather superheroes dressed in super versions of running clothes would make sense—skin tight clothing with lots of skin exposed. This, of course, assumes that the super heroes have the human need to stay cool when being active. A superhero that had no need to sweat could wear whatever they wished—the concerns of mere sweaty mortals would matter not to them.
Considering this, it would make sense for female superheroes to wear the same amount of clothing as competitive runners—that is, not much. However, the same would also apply to male superheroes.
While wearing minimal clothing is a good idea when active under warm conditions, like runners facing cooler weather, superheroes would need to cover up more to remain comfortable and perhaps avoid hypothermia. Practical and sensible superheroes should also consider following a standard practice of runners: wearing more clothing to warm up or when waiting to compete, then shedding clothing when it is time to get down to business. Since hanging out all day in sweat-soaked clothes is uncomfortable, sensible heroes would also change costumes when they can. And shower.
Unlike runners, superheroes spend much of their time in combat and this would impose another set of practical considerations in regards to clothing. Since superheroes tend to fight hand to hand, it would be unwise to have costumes that provide a foe with easy handholds. As such, tight costumes without extraneous material would be the best choice. Capes would, as always, be a poor choice.
When engaging in combat, it has always been a good idea to have protective gear. Some of this protection is intended to deal with the incidentals of combat, such as ending up in contact with rough surfaces (like being knocked down in the street) but most of it is supposed to provide protection against attacks. This protection usually takes the form of armor, ranging from ballistic clothing to powered armor (like Iron Man wears).
Armor does have the usual trade-offs: it tends to restrict movement, tire out the wearer quicker, and create overheating problems. As such, heroes that rely on speed and freedom of movement might be inclined to avoid armor or at least keep it to a minimum. The classic Batman, for example, did not wear any armor. However, as anyone who plays games like D&D knows or faces combat in the real world, armor is generally a good idea for those who are going to end up in combat. Otherwise all those knifes, bullets and ray blasts will be hitting your skin.
To be effective armor must at least cover the important parts (usually the head and torso) and that means that exposing a lot of skin (especially cleavage or the abdomen) is a bad idea when you are counting on your armor. As such, the typical fantasy drawings of heroines in armor are absurd. Or, as a veteran D&D player put it, “if the enemy can see your cleavage, they can cut your boobs.” And no one wants their boobs cut.
Superheroes who have powers that make them invulnerable or otherwise grant great defensive powers do not need to rely on armor and they can safely wear whatever they like; such as Power Girl’s famous cleavage window costume. While the classic Wonder Woman relied on her magical bracelets, the updated version seems to be close to Superman in her ability to withstand damage—as such, she would not need to rely on armor for protection. Superman, of course, does not need armor—his skin is almost certainly stronger than anything he could wear. As such, a superhero who still had to deal with the sweating problem but did not need armor would want to wear as little as possible, be they male or female. Perhaps this explains why Wonder Woman still dresses the way she does.