Here's the original image we're going to use, to start off. These sprites are primarily pixel-overs, but as you'll see in a bit, don't let that fact fool you. It can be a bit tricky to compress all these details into a small space depending on how detailed the original art is. When we go to resize this down to 64x48 px--make sure to keep the aspect ratio intact when you resize it--we'll see that it can only be resized down to 64x44 or 70x48. What we need to do is trim the sides down bit by bit until we can get the aspect ratio at that sweet, sweet 64x48 canvas size. The reason why keeping the aspect ratio intact is so important is for two reasons:
First of all, you don't want the sprite to look stretched or squished.
Second, so that the Pokemon is large enough on the canvas so that you can fit more detail in. The Pokemon is the focal point of the sprite, after all.




Much better. You might want to save this image and keep it nearby as a reference, because you'll probably be needing it later on.




This is what we'll be working with. In my program, I'm able to create multiple layers and change the alpha / opacity, so it might help to have that.




Start by distinguishing the line art of the Pokemon. the Pokemon is the focal part of the piece, therefore most of your focus should be used on it. Even if there is no line art in the original art, blocking in the shapes will work fine. Whichever you prefer, as long as the end result looks to be in a similar style to the original art. You might need to compress certain details to make sure the sprite is readable. You'll probably want to frequently reference off of the original artwork, as stated before.




At this point, you can try to figure out what you want to do with limiting the palette, but I honestly just judge it as I go. I'll be combining and/or getting rid of a lot of these colors, but for now it helps me differentiate the different pixel clusters and get an idea for how I want the shading to look. Speaking of which, do your best to make the most out of dithering! It helps to blend colors.




In the games, most Pokemon in the sprite have a light-colored (whatever the palette's equivalent of white is) 1 px thick border. You usually wanna add that. I made it yellow here just so I can distinguish it from the background I'm gonna be adding.




For the background, you'll generally want to block in pixel clusters of different colors; try to mimic what you see and reference back to the artwork as needed in order to make sense out of specific details. Here, I made the ice crystals have more prominent outlines so it's clear as to what they're supposed to be.




Now, time for color reduction! We seem to have a problem: This consists of 11 colors. With the program I use, I'm able to see exactly how many colors I've used for a sprite, and I can even see exactly what those colors are. This is a hugely helpful tool to have. First of all, I combined the yellow and light orange together. One color down, 2 to go.




Second thing we can probably do is combine the dark blue and black. As a result, I also had to even out the contrast on the other blues by making them darker. I also combined the base red with the shading on the white spots too.
Last but not least, you need to make a 1px border around the edges of the canvas (or whatever your equivalent to black is in your palette, for me it's navy blue).

Finishing touches, then it's done.