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These are clearly your first attempts, and you've fallen into a lot of the traps that new spriters struggle with. Don't worry, we've all been there! Try reading this tutorial thread which goes through some of the basics like shading and colours and then have another go, and we can give you some better feedback on what you need to work on. :)
Your first sprites are like my first attempts at making fakemon. Don't lose hope, bro. You can be as great as Ryan with a little practice and a hardcore montage.
Compared to your original sprites, that's a big improvement. However, it does still have quite a ways to go. The shading on the head is a little awkward, and the head itself seems kinda empty with just that single tiny eye. Maybe that's the effect you were looking for, I don't know, but the shading on it is a must.
The head still looks flat regardless of the shading attempt. Here is a simple and informative image quickly searched through google when shading spheres or sphericaliceobjects:
The eye is lacking some dimension as well, so perhaps add very few shading just below it.
Another big problem is that you shouldn't be using official Pokemon sprite parts and pull it off as a scratch sprite. Use it more as a reference. I can see that you've used Registeel's hands, and I understand that you're a new pixel artist, but just letting you know.