I painted a Bratz (but changed the hair color and eye color to match my dds) and painted a pink shirt on her to match the pink shirt my dd wore with the pants. It turned out great, but painting things that 'resemble' other things and selling them gets you in trouble with the copyright people. She did an awesome job on that jumper though....your dd will enjoy that.
Oh and I put 'resemble' because that jumper looks exactly like Jo Jo but I've heard of people listing things on eBay that are in essence Jo Jo or Strawberry Shortcake....etc and calling it Bo Bo or Strawberry Savannah....etc and saying it was 'like' the real thing. That still could get you in trouble, especially when those originals are so close to the real thing.