Just a warning, but my criticisms may come off as harsh. I only give my criticisms in this way because I want to see you improve, because I truly believe that you will be able to improve this design and make it great, and sugarcoating it would take away from what I’m saying.
First, the formatting. You appear to be using a sprite where the pixels are 2x2, when you should be making changes in a 1x1 pixel size with a 1x1 pixel brush. It’ll let you add in much more detail.
Second, aside from the snake tail this is a recolor. Not a great one at that. The colors are very saturated and they clash heavily with each other. I’d suggest limiting your pallet to three colors at most. The colors are also flat - they don’t have any shading. I’d suggest starting with a pallet of two key colors with at least four shades to play with. Look at official pokemon sprites to get a feel for how they’re normally shaded.
Third, the only real change made to the sprite is the snake tail. That isn’t enough to call it a delta, but if you expand on the concept it could be very interesting. Maybe give it large fangs, reptilian eyes, change its body shape a little, go wild with the concept of a poisonous snake, or even a gorgon!
I can only hope you take my criticisms to heart and really try to improve, I’d love to see this design reach it’s full potential. I’ll be rooting for you.