I'm looking over several different Japanese shows that use giant monsters for reference. You might see an enemy that originally appeared on some version of Power Rangers, or a monster from Godzilla's universe. There's a few details in my CS about the setting and where our enemies will come from initially. 

You can use any Ultraman as a starting point, but give them their own name and backstory like I did. I'd say only Ultra King and Ultraman Taro are cannon in this game, Taro just being one of the guys who trains us all.

~KL~