Alright then.
I like the colors you've picked for each of them, they really stand out from each other which is great unless they are part of an army. Now given the similarity of each outfit, I'm assuming they're in some kind of school campus?
I'm seeing the preppy look on all of them (blouse, blazer, vest, tie, slacks, skirt, and leggings seen in a lot of schools.)
Is there a dress code enforced on them? How strict is it? Are they all from different schools? The whole line up makes the most sense if everyone is from a different school, with a different dress code.
If they aren't from the same school or the dress code is not all that strict then you might need a bit more variety in terms of style. Have some goths (The grey boy) , some punks (The red boy comes to mind indigo girl too), Have someone wearing long flow things (Green girl), Someone who looks more sporty (Blue boy again. Tall collars are good for hiding and also the purple girl.) Etc.
I think I've already said my piece about the gray body so I'll skip him. Glasses might look good on him too. Glasses instantly make people look smarter.
For the blue boy, the hooded sweatshirt is seen a lot and it makes him look kind of young. It also obscures his hair which is one of his most identifying traits. Maybe you could opt for a high color or a scarf instead or a high collar, or if you dont mind props a book or some glasses that he can push up his nose? Unless you are trying to make him look young, in that case you could make his entire hoodie bigger, have it sag more on his tiny body and have the hood almost bury him.
The green boy looks like he's some kind of a jock, The way he is now does not look anything like the description you wrote for him. If you intend to keep the jock look, have him look at things from the corner of his eye, like the girl clinging to his arm. The side eye instantly makes people look less certain about something. Athletes also tend to have this air of confidence and elegance around them so if he has neither of those things you can make his clothes ill fitting. It would look like he's trying to fit a role but isn't entirely successful. Not to mention ill-fitting clothes could give him a reason to be awkward physically since he'd have to constantly adjust his clothes.
The red boy should have the most dynamic design out of all of the boy since according to the list he is the most... out there of them all. You could intensify the red to make him pop a little more. I have no idea what he is so passionate about but it looks to be some sort of clean artistic craft (sewing, writing, collecting knives or something eccentric). That means he can go two ways to show it. His clothes be perfectly fit and tailored to contrast him from the others and give the impression of someone who is highly polished. It would also be super weird so see someon who is super neat and polished out side of an administrative building, black tie event, or the victorian era. The other way you can do this is making him look more disheveled, like he spends so much of his time and energy on his job he has no room for anything else. In that case make everything messier, let his shirt tails hang out, let his hat have a bunch of weird things sticking to it, let him be covered in strange stains or scuffs from what he gets up to. I'm imagining he has a very intense stare too, you might be able to hint at that through his hair (having a single eye peeking out occasionally.)