>>41116202>there's no reasonThere is. Pic related.
Sonia is a human. They don't care about what's below her coat. She's not the biggest selling point of the franchise (a pocket monster).
Hatt, on the other hand, was designed to have a tiny body, covered by a flesh-like dress.
Also, not having the body show up after seeing it in her pre-evolutions would've been stupid.