That animation is called "Dexter's Laboratory" and The Powerpuff Girls are the work of the same company. The style of painting must be the same. There is also Dr. Steel in Coolcats, and the silly villain Dr. IQ in Arare.

, a cute little girl and many doctors are so old. They are defined like this by animation. There is no way. If it is not enough, I will help you think about it. If you are satisfied with my answer, please accept it.