This issue is titled "The Battle for the Right to be Called… Earth's Mightiest". And to see not just the three teams featured in the preview and past issue (Avengers, Defenders of the Deep, and Winter Guard), we now have a fourth team.
spoilers:end of spoilers
Squadron Supreme of America, with Hyperion, Power Princess, Nighthawk, Doctor Spectrum, and Whizzer. It doesn't say which incarnations of those heroes are present, as last time I know there are two Zardas, the depowered one from Earth-712 and the one who stole her powers.
I did hope we'd see the two storm/thunder gods face off, Thor fans are sure to be displeased his girlfriend-to-be (She-)Hulk outmatched not just Perun but Chernobog as well.