Wooyoung
Start;
Wooyoung tended to wear more impractical, nightclub clothes in my mind at the start of the story, so stuff like this. It kind of resembles his mindset at the time (You'll understand when you read.)
Further into the story;
He begins to wear clothes that are more suitable for the environment, but hold elements of both Atiny and human culture. So like this for example. Wooyoung also took to wearing one side of his hair in a braid, because he thinks it looks cool.
Mingi
Throughout the story;
Mingi, who is an intellectual, wears comfy clothes that are good for wherever he wants to go. He's a smart bean when it comes to clothes, and his clothes don't really change throughout the book. He only really adds the element of Atiny pants, for he found them comfy. He doesn't care about style as much as Wooyoung, and it shows in a good way. Mingi also loves wearing his hair like the Atiny, so in braids with feathers like in Pirate King. Also the same colour, so a blackish blue.
Hongjoong:
Start of story;
Hongjoong, like Mingi, isn't big on looking overly fashionable. He thinks of what's going to be easiest to wear and what suits the climate. So predominantly loose shirts and baggy pants. He also has red hair, because I love it.
Further into the story;
Hongjoong is probably the person who best took on the Atinyan culture, in what he wears. He found their clothing cool, so started wearing it more often. By the end of the story he only really wears this kind of clothing, unless he's meeting the Captain. Hongjoong also wears the Atinyan clothing of a higher up tribe member, for he is closer to the Chief and she told him he was allowed.
Yeosang
Throughout the story;
Long story short, Yeosang in this story is a little badass, and that shows in his clothing. He likes to look intimidating, and have lots of places to hold weapons.
Monsta X wear clothes that they usually would in real life. Excluding Wonho and Changkyun, but you'll find out why in a minute.
Got7 wear farming kind of clothes, and just comfy clothes around the base.
NCT wear combat gear with lots of weapons such as guns and knives, but also are going to be seen in more comfy clothes for the majority of the book.
(All drawing credits to original owners, art not mine)