Copy a Pokemon sprite image from a resource online.
Open Microsoft Paint and paste the Pokemon sprite into the Paint document.
Zoom into the small Pokemon sprite using the magnifier tool and center the sprite so the entire image is in view.
Select colors by clicking the "Edit Colors" option on the upper right. Use the slider or type in a numerical value for the amount of red, blue and green to create custom colors.
Paint the Pokemon by using the paintbucket tool to cover large areas and the pencil tool to paint individual pixels. When you are finished repainting the Pokemon, click on the floppy disk icon to save the artwork.