So I just noticed on the Marvel Puzzle Quest official facebook page that Moonstone joins to Super Villains in the Race for Iso-8 episode. Has anyone else seen any mention of Moonstone?
Nope but I’m assuming as the maps cycle, the story will continue on and eventually Moonstone will be revealed. 
That’s correct. At the moment, you’ve got Venom, Juggernaut and Bullseye zipping around, but they’re not the only Dark Avengers or allies on the prowl.