FDAFSDKFSDJHSDFHJ I FINALLY, ACTUALLY HAVE TIME NOW

Okay, so I'm just going to try to give you general pointers based on the stuff that you have here, since I can't exactly critique one thing from the other because I'm not 100% sure what you consider old and what you consider more recent (beside the PNG-JPEG difference).

Quite a few of the recolors you have look incomplete, as in certain parts were not recolored. I also see that you're using palettes from other Pokemon; that's totally fine, but you might be limiting yourself to JUST to color ramp of the Pokemon who's colors you're using, hence why Ninetales' outline color is still light brown, for instance. I'm sure you're probably already aware but never hesitate to use the color sliders in Paint. Basing your colors off of the colors of something else is totally cool--it can be really hard to pinpoint that exact color you want--but try to deviate some from them, maybe.

Some of the others, such as that cyan-colored Flaaffy, lack efficient contrast, therefore I have to squint to see the difference in the shades. Very bright, highly-saturated colors are tougher to scale down into the darker tones because you have to make them really dark before you can actually see some contrast. Yellow and cyan are good examples of these "tricky" colors.

My suggestion? Try varying your saturation for your colors. Lower saturation means that the color contains more gray and is less vivid. For really bright colors like cyan, it helps to lower the saturation a tad as you get into the darker shades.

With fusing, copy-and-paste fusions are alright for just pixelling casually / just starting out. However, you can't just paste the appendage from one Pokemon onto the other and call it a day. A lot of the time you'll need to maybe change the line art some, and even the shading.
Vulveeon is a good example of I guess what I'm trying to get at, here. It looks like the Eeveelution tails were just haphazadly pasted onto Vulpix's rear end. There's just an Umbreon tail that's magically attached to Vulpix's thigh. I mean it would be better if the black maybe transitioned to the brown in some way, or you changed the color of the Umbreon tail, or changed Vulpix's main body color...but as of now it's like nothing is really connecting it to Vulpix, y'know?

Sorry if my explanations are a little wishy-washy. I can get...ehm, pretty bad with that. If you need me to clear something up feel free to just ask me to elaborate! c: