I love these enemy designs. You're perfectly threading the needle between creepy, funny and lewd here. The gameplay is quite fun as well, since the enemies all have different movement patterns. The three characters also all play differently, so there's some replay value. This is pretty cool, well done!
That said, I think it could be interesting to throw some more complications at the player. Powerups, high-value 'bonus' enemies, maybe even the occasional mini-boss battle. That sort of thing. Still, this is pretty great.