Some really nice stuff you have here!
If I were to tell you one problem I have at the moment, it would be your feet. They just seem stuck at awkward shapes of poses a lot and don't quite fit the movement your characters possess (or don't in some cases)
With
this piece the feet are very oddly proportioned, and don't match each other at all. The shape and size don't match, and they just seem very unnatural as a whole.
This and
this piece both have a similar problem, in that the feet just seem a little awkwardly bent, and don't sit right with the movement or position the body of the Pokémon is in. Oddish seems like its foot is stuck in that position for good, whilst your Espurr looks as though its ankle is broken, since the foot is twisted a little too far around.
The problem with
this piece is that she has two left feet. Literally! Or at least it looks that way, the way the toes are arranged. If the foot was the correct foot (the right one) and was perhaps twisted a little more to point "towards" the viewer, it would be a major improvement!
I don't mean to sound rude or mean typing that, and I apologise if I came across like that; I just want to try and tell you how I saw them, to try and let you know where you should try to improve. Otherwise your drawings are cute, albeit with some shaky line work here and there, but that will improve with time ^^
All in all, some good stuff, with a lot of potential, I look forward to seeing more!