C.S.
It gets really interesting. My 9 year old fits some Ladies Small and even some Mediums. She also fits some girls 16's and XL.
Today, we tried to find a pair of sweat pants and the ladies pants were too long, the girls XL was too long and the girls L were too snug.
There are still plenty of shops for you to go to.
Old Navy
Target
Penny
Kohls
Justice has some plain and some wild clothes.
You may also try a sporting store if you are looking for T's to play in.