You are a very talented spriter, my favorite is definately your sprite on the seventh row. It is a completely original idea and came out very nicely
On your first three fire pokemon, I think you should put one or two more shades of red/orange in each of the flame areas. Right now they seem a little flat and don't really match the balanced shading on the rest of the sprite.
The shading on the first one is prefect because the amount of shading you have done comppared to the fire is nearly perfect, and the second one is alright as well. But the last one may look even better with more shading in the red/orange area.
I sort of did that with this sprite, or course its way to big to be a game sprite but you can see what I mean nonetheless,
http://i95.photobucket.com/albums/l134/POKEMONMASTERALEX/FlarichuScratch-1.png