Space police is a good idea, and I may switch to them later. But here is what I did with what I had on hand.
I used a placeholder head for Red Skull.
Mechanic, Officers, Commandos with some serious hardware, Commandos, Elite Commandos.
I also took two flat transparant blue 1x1 bricks and made a cosmic cube to be fought over. All I need now is a battlefield and someone to play with.
The Explorians clearly aren't the best choice, but until I order some replacements they will suffice. And I'm pretty happy about how the Atlantis guys turned out, bringing some of that classic green look to Hydra (HAIL HYDRA!).