I've covered non-costumed male villains and now female costumed. Because in both Super Sentai and Power Rangers, we usually get more non-costumed (face) female villains and more costumed male villains. The reason to this I believe has to do with a key social aspect of females believed to be beauty (which I don't agree with it having to being a sole aspect to concentrate on) and the male villains having to be scary and powerful.
She is the first villainess in Power Rangers that was full costume, not like Scorpina who was half and half.
Necrolai (Mystic Force)
She did get a human form at the end of Mystic Force but I count her as a mostly costume villainess.
She was once human and we do see her human form from time to time but I see her mostly as a costumed villain.
Metal Alice (Megaforce)
She had no human form like Archerina, she was all costume, she only appeared in a handful of episodes.
Levira (Super Megaforce)
She had no human form, she was all costume.