Round 1:A one on one fight. Round 2:A battle between all there followers without there participation (the honour guard,Desad,Balrogs,Sauron etc..) Round 3:Melkor before he entered Ea vs. darkseid with the anti life equation.
Round 1: Darkseid beats first age Melkor. Melkor in before first age beats Darkseid.
Round 2: If this is all of melkors minions throughout all of time until the one ring is destroyed, melkor curbstomps. I think he also wins with only all of First Age host but I'm not sure.
Round 3: The Anti-Life Equation (and the Life Equation) is equivalent to (I assume) the Flame Imperishable. So Darkseid curbstomps.
Edit: More research into Anti-Life Equation makes me come to a conclusion that Melkor alone is equivalent to Anti-life Equation and The Life Equation is equivlent to Flame Imperishable.
Why? Cause Melkor is the root of ALL evil.