this is truely a work of the gods.
those character designs. just look at them! they just OOZE originality! and the hairstyles, they are so new and refreshing! however, one fatal flaw you forgot to include was Girlchan herself. My god, if only she had been added, i'm positive that these characters would have grabbed EVERYONE'S attention with their stunning, flawless designs!
I particularly love Kenstar's nose plaster. it says, "hey, i'm tough, and i can get hurt, but it's totally cool, i can take that, I'm a man!"
And Yusuke's brooding look tells us that he must have had a horrible past. ( ;_; )
Anyway, a good tribute to 2 of the most original characters ever created. I applaud you, and thank you for gracing us with your beautiful arts.
Good day!

I actually rather like this picture, something about the choice of hue (not the colors themselves, but the tone and saturation at which they're set) is really easy on the eye, good job with that. Since I don't know much... Well, anything about the characters in question, I can't actually give any advice on your rendition of them, nor will I mention the lack of background or anything 'cause I think all this is meant to be is a simple drawing of them, so that's fine.

Right. With that out of the way, proportions. Your shoulder width and size of the torso in relation to the head is correct, but their arms are too short, particularly the top part of the arm. This also hints that their waists are too short in relation to their heads. That's probably the main thing throwing it off, but if you keep it in mind it's really easy to fix in future drawings, and you'll see quick improvement for it.

The simple shading is nice, if a little undefined in some places, all I'd tell you for that is to add a little more in certain areas, and try some highlights on the skin. Maybe run one across the hair, too, it'll appear less flat then. Also, wtih the source of light which I think you've drawn, the guy with the brown hair wouldn't have that shadow on our left. That's all!