Your poses and anatomy are real nice.
I think you could expand into backgrounds sometimes.

That's a tough one. The definition of good and bad artwork can differ from people to people. For example, this is in my eyes a "bad" picture: http://www.furaffinity.net/view/20785606/
Big artist right there, so why would I diss this picture? Well, great color work and you really gets the feeling of deepness in that picture, but that vagina of hers is just not working out for me. It's not horizonal, it's not vertical but it is diagonal and that is neither fitting for a reptile nor a mammal. So in my eyes a plat colored picture can be just as good as an complex coloration with crazy background and all of that.

In general I'd say it is a matter of taste. My personal preference would be cute faces and I think your artwork is more normal, I guess. Not overly cute but then again, someone else might want more realism or neutral facial expressions. I'd say your "Primadonna" picture is the cutest of those you've done, (Excluding slugma but there I'm simply biased.) and they both have pretty plain expressions.

As long as you draw the genitalia in center of the body, gets limbs in sync and no strange body bending then I'll say "you're doing a fine job."

However, here are some suggestion on what you can do to try out and see what you like.
1. Add backgrounds. (Easier to see a story in a picture)
2. More muscle or body fat. (Creates a more 3D effect but alter the pokemons original design)
3. Perspective play. (Closer to the camera the bigger it is.)
4. Unique sex position or body pose. (Some creature are more bendy than others.)
5. Alter coloration. (Grass is blue at night and a sunset makes dark colors look lighter and stronger.)

That's some suggestions that I can come up with. Hope this was helpful.

Your feral art is some of the best out there. I don't really know what to tell you in regards on how to improve, but I'll give you some ideas to practice.

One thing that a lot of artists want to improve on is backgrounds. Try all different types of backgrounds: forests, oceans, houses, wide open pastures, waterfalls (water is a hard one to tackle), etc. Also, creativity, especially in regards to Pokemon can be something that can make your art stand out even more. Just let your creative juices flow, and your art will be better for it.

Hope this helps.