Watch all the different poses Scratch Cat can do (but there are many more inside). Using variables in the "scratch" sprite, tell the rest of the sprites to switch to what they need to switch to for customizing your own Scratch sprites with unique eyes, mouths, legs, ears, tails, and arms.
Me myself and Scratch Cat. Ignore the choppyness of the leg animation please :P If you want the scratch cat to be in a single costume, screenshot then crop. If that's not enough, repeatedly copypaste the costumes onto the "Scratch" sprite.