K well for starters... Your outlines are choppy. Try to find your own style. Example.
Notice what colors to use for the outline and what places to put them? But sometimes even that formula may not work. Notice the Eevee on my sig? In some places you have to decide where to put black/dark colors. Otherwise it will look to light.
I feel like doing revamps right now I started with Pikachu... here it is, i will just show what I make after I make it!
Like?
You save it as jepg... don't even use that with sreencaps >< You ALWAYS save sprites/pixel stuff as png. There are of LOADS other saving files. But png is the best for that kind of suff. The ody looks VERY flat. And the out line is choppy.
Here are 2 more, Ninetales and Butterfree
K I thing the first Pika was a mistake. These are saved as png. But you
can resize, but not like that.
MS Paint>Image>strech/screw>put EQUAL numbers. ex. to make it twice it's size, 200 200. But the last two boxes are for who know's what. And also when you do resize your sprite, you have to re-do shading, out line and other such.
The revamps themselves are good, but Butterfree's wings have very light shading. usualy it has all shades on it when shading.
Ok than forget the Ninetales, Butterfree, and other Pikachu
D/P Meganium -- G/S/C Mega!
Looks more like recoloring from here. And the whole outline is black. I don't remember G/S/C sprites only having a black outline.
Overall, 4/10