Darkseid and Doom VS Galactus and Thanos
Both teams get a week of prep with their smart guys.
Doom gets a week of prep, Thanos gets a week of prep.
Darkseid and Galactus only know what their team mates tell them about each other.
So who wins this? I think Darkie and Doom have a good chance, since Doom has taken down Galactus before.