Is Shanghai actually fused with anyone? The only difference I can see is eye color, and that varies depending on artist.
Yuyuko + Yukari = HOT
Utsuho + Tenshi = We're doomed.
I've added notes to the bottom of each picture saying who's been fused. I'm pretty sure about most of them, but if I'm mistaken on any of them please don't hesitate to make the necessary changes.