Δ° hope im not being rude but i think you should use more vibrant colours to make the chars attracting (dont forget to use more different colours on your OC's too) , you should practice on anatomy and face the body looks mechanical when you draw it try to draw more natural :P Hope thi helped you
anatomy wise they could improve a bit, most of your ocs are a bit lanky so you could maybe make them a bit bulky-ier around the shoulders and upper arms, all of your ocs are the same color so you could probably do some research on which colors go well with blue