Wow. These are your first sprites? For a noob, these are really good. But compared to other peoples sprites, they are pretty average. Out of your mixes, the marshtomp mix is the best. I like the look of the trapinch/togetic...but what is on the dragonair/altaria's head? xD.
The best revamp is the venasaur. The blastoise needs more shading though...
Keep practicing and you might get really good ^-^