What men transform in anime?
     The Sailor Starlights (from Sailor Moon SS)...
     Ranma (to Ranma-chan)...
     ......

Ryouga, Mousse and Genma (from Ranma)
Tenchi changes into Battle Armour Tenchi, but that doesn't *really*
count....

What gender is Ryo-oh-ki? could it count?

Ryo-ou-ki is a female. She lays eggs.

Kun-chan...