Sleeves for humans aren't too terrible, if you have a good pattern. But klickies don't have the arm movement to make sleeves easy to get on, and they'd have to be super tiny.
So . . . I tried sewing a dress. It did not go well. Klicky heads are huge, but I don't really want to pull their heads off to change their clothes.
Maybe we need to look to the Sylvanian clothes for inspiration. Or I should stick to pillows and blankets.