True, but Spawn has other powers too. Healing, Energy Blasts, Elemental Control, Alter Matter, Fly, he can make anything out of his cape, etc. Not to shoot you down, I like Batman too, but Spawn's only weaknesses are Lack of Necroplasm, and being beheaded. Batman doesn't have any swords or knives, and batarangs don't have very large blades at the tips, so it's unlikely he'd lose a head to a batarang. It just seems Batman's chances of winning are really low. He has a chance mind you, but it's slim.
Batman has fought darkside and supeman. Both have punched him he still gets up and fights back. Batman has beaten Superman a couple of times. Superman would destroy Spawn. Spawn's biggest mistake would be sending Superman to the sun. Superman will het Spawn and rip him apart.
We went from Batman vs Spawn to Super Man vs Spawn? Spawn would not think to throw superman into the sun because he isn't strong enough to throw Supes that far. Other then that, yeah I think Supes takes the win