First off great to see you trying.
Few pointers:
Never save as JPEG/JPG-it ruins the quality always save as .PNG.
Never stretch/skew them-This also runs the risk of ruining it. If you want to have a zoomed in few. Zoom the page in then press Prt Scr button on your computer. This will capture the whole computer screen as a screenshot. Then just paste and select your sprite. This doesn't run the risk of ruining the sprite.
I would be able to give better help if they weren't JPG. But from what I can tell your not doing a horrible job.
Just make sure that when you swap pallets that you don't leave any of the old colors left. (such as the outline color on your evee/absol)
There are plenty of great fusions in this thread to look at. Or stop by the Fusion Sprite game in the appropriate board and you can see two that I just did.
I have some sprites for people to critique, aside from the recolour, feel free to guess what was in each one.
also this:
Gotta say this is probably your best one. The others just look pasted together. I would suggest trying to do what you did here to the others. Great job good to see people trying.