I'm here to help!
don't go straight in to scratch spriting, start like I did with revamps, but dont just recolour, study how the newer sprites look and make the older sprites look similar. study the shading, how the shape of their body has changed, the way light hits the curves etc etc.
when you have revamps down, you should have a good idea of what makes a new generation pokemon sprite, anything after D&P has a simpler style than anything before, RSE sprites look messy in comparison now.
this is really poorly written as I've not done any spriting for a long long time, and I'm ridiculously tired, but you get the idea, study sprites well and learn the style till you develop your own, and try and make the sprites look as natural as possible. also, with good concept comes a good sprite, so try and work on your concepts a little more.
Maxxa