Your art is very very nice! I suggest adding backgrounds if your up to the challenge! 
Hello! I like your arts! You could make the character’s head a bit bigger. Because i find them small when i think about a Roblox Character…
I agree, the art itself if great but it seems that the proportioning is off. 
I’m no GFX Designer or Artist , but that definitely is very nice!
Piggybacking on others suggestions, the proportioning (specifically the head) is off.
The third picture in particular looks really good, but going off from this
The folding of the clothes can be definitely be improved on, the folding of the clothes on the left arm of the third picture looks similar to bandages.
Great work, keep it up! 
It looks stunning! You have a unique, energetic style. You sure appear comfortable drawing clothing.
My only suggestion would be to add shading. That would really take your art to the next level and add that “wow” factor.
The shading and detail is pretty good! But, the characters are pretty bulky, and the heads don’t really fit with the bodies. In the first picture the arms need to be smoothed out. Unique art, I suggest using FireAlpaca, Adobe Xd, or Inkscape, because Procreate is not that good of a software.
Yup I’ve always thought of that but I’m afraid the head is too big…
But procreate is the beat app that you could get on an iPad since I don’t have a drawing tablet for drawing on PC
I’m no 2d artist, but from a someone who sometimes buys 2d art, this is really good!