The Survey Corps
Commander Handsome (Erwin)
Abilities: Superstrength, flight, bulletproof
Uniform: Basically just your normal superhero spandex; color scheme is dark green with some white. I haven't really given much thought to what the uniform color design looks like, sorry. The Wings of Freedom are a roughly fist-sized patch over the left breast.
Notes: Very classic superhero aesthetic, he's pretty much Superman... that's it. He does the "Clark Kent thing" in that he wears heavy-rimmed glasses when he's Erwin, but takes them off to become Commander Handsome. He does not actually need glasses.
The Nose (Mike)
Abilities: Heightened sense of smell and premonition. Able to see the future incredibly clearly up to 5 minutes ahead of time on occasion, but usually it's a more generalized ability to "feel" how a situation is going to go.
Uniform: Very basic fitted khaki pants and a long sleeved shirt, solid leather boots, wears a heavy jacket; something akin to an Army jacket. It's all very sensible because he used to wear an outlandishly "traditional" superhero costume when he first started out (with the cape and everything) but after he and Erwin partnered up he realized how much of a tool he looked like so he ditched it for some more sensible gear. He wears a common fitted domino mask. Wings patch can be found on the left breast pocket of his jacket.
Dr. Scientist (Hanji)
Abilities: Martial arts (second degree black belt) and mad scientist inventor
Uniform: Similar to Mike's in that they wear pants and a shirt that are relatively fitted, but they wear a lab coat over it. They don't wear super heavy / solid boots though, they're still pretty well-made but offer a bit more flex and articulation at the ankle. They have a utility belt that they attach all of their weird little gadgets to. They engineered the grapple gear** for Levi and they wear it as well, they just don't use it as much. Their "mask" is actually just a set of old aviator goggles. Their Wings patch is in the same location as Mike's: left breast pocket.
Notes: Batman crossed with Dr. Horrible
The Hawk (Levi)
Abilities: Extra-sensitive hearing and sight, stronger than average but not superhuman strength like Commander or Scarf
Uniform: Gray and black catsuit, wears grapple gear** over it and has a utility belt like Hanji that he stashes his gear on (e.g. stun gun, collapsible rod – all non-lethal except for a knife). Depending on the job he might carry a tranq gun. Wears a domino mask, the same as Mike. His wings patch is much smaller and on his left shoulder since he does mainly stealth work and having a patch right on your chest next to your heart makes for a pretty good target.
Notes: Pretty straightforward, he has an edge with his senses being extra-sensitive and his body being stronger than average, but he isn't superhuman really.
**Grapple gear: it's essentially the 3DMG except there aren't any blades ergo there is no need for the trigger grips to be so large and separate from the gear. The triggers slip over each hand so that it is perpetually being gripped in hand and only takes tightening a fist to "pull" the trigger. The pitons / cables are still shooting from the hip. (idk if that made any sense)
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Red Scarf (Mikasa)
Abilities: Superstrength and flight
Uniform: Really easy, it's just the military uniform from the canon-verse without the cape and in darker colors (black, gray, olive green). Also a big red scarf / cowl (duh) that obscures the bottom half of her face; it tends to pull away from her face when she fights which is why everyone knows who she is.
Notes: Technically she can fly when injured but flight requires a great deal of muscle conditioning if you don't want to be uncoordinated which is why she hates being injured so much; normally she floats /flies everywhere Marceline-style when she isn't incognito.
The Hunter (Sasha)
Abilities: Keen eyesight, better than average but not superhuman; otherwise normal
Uniform: Flexible but durable fitted clothing, hunting coat; pretty much just looks like she's wearing super lightweight hunting or military gear. She carries a fairly basic bow and uses mainly trick arrows; she does carry a real ones just in case.
Notes: If you watch Arrow you've got a pretty good grasp on Sasha's powers and her uniform. She's pretty much Oliver Queen except without the money or the murder lording that he did in season one.
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Beauty & the Beast
Historia (Krista Lenz)
Abilities: Telekinesis focused through custom-made amplification rod since her powers aren't as strong as others
Uniform: Uhhh… Sailor Moon made a bit more practical. I actually did art of this that came out halfway decent. This is going to sound very odd but it's a seifuku that's been a bit loligoth-ed and has a fitted longsleeve jacket over it, she also wears a tiara that offers additional help focusing her powers. It doesn't sound it, but it's actually pretty practical. She has the only uniform that isn't dark colored; the entire thing is mostly pastels. She wears a masquerade mask that covers the top half of her face, it's very shiny.
Notes: She's Sailor fucking Moon.
Savage Dancer (Ymir)
Abilities: Shapeshifter, her "non-human" form is very lanky and just under seven feet tall and she has wicked claws; she can stretch her limbs independently a further six-to-twelve inches. This is actually something that I could conceivably art and I should do it. In spite of looking like a very gangly monster she's actually very graceful. She doesn't wear a mask since her features shift enough to make her unrecognizable.
Uniform: She wears a simple brown unitard that stretches with her as she shifts.
Notes: Nobody remembers Historia or Savage Dancer working alone or with anyone else, they are referred to as a unit as "Beauty & the Beast"