The Fantastic Four VS Viltrumite Invasion

The Fantastic Four from Earth 616 VS Invincible

For this battle there will be 3 scenarios all of which share one key aspect that being the other heroes and villains of earth have vanished.

Scenario 1: The Four have no prep time and the would is immediately invaded by 3 low to mid level viltrumites.

Scenario 2: Assuming they win the first encounter Conquest with a small army of 20 Viltrumites head to earth but the Four have a month of prep time.

Scenario 3: Assuming they win the second encounter the rest of the alien race shows up to earth led by Thrag. The Four have 3 months prep time.