Very nice picture! I like the style that is quite different from the cartoon original but still very clearly Kim and Shego. Kim's and Shego's hair are nicely done up, and their clothes are well reminiscent of their usual gear.
I would have liked to see their feet, though!
The one thing that strikes me, though, is that it looks like they have been drawn separately and then put together on the same paper. (I do that quite a lot myself). I get the impression they don't really interact. Although Shego is really taller than Kim, here it seems she is shorter, and for some reason staring at Kimmie's neck. If you move Shego up so that she looks Kimmie in the face I think the overall impression would be better!
This drawing is fantastic! I'd have to say that my favorite technique you used on this piece is the reflection of Shego's green glow on the edges of her hair. I haven't seen any art that depicts Shego and Kim fighting in this way, so I find it to be exceptionally unique. I like the destroyed, humbled expression on Shego's face - it conveys the emotion of Kim winning the fight.
I definitely agree with the previous review: I'd like to see the feet in this drawing. However, with the bending of Shego's knees and the way that their feet would be positioned if they were shown, I do think that the slight height advantage that Shego always has over Kim is humbled well with her overall slumped-over appearance.
This is a creative take on the battles between Shego and Kim, and I do enjoy the skills and techniques used on this piece.