With the mod overlords having taken down the barrier separating Goku's world from Superman's, the two aliens meet and quickly start up a bromance. Their combined power ushers in a new state of world peace. Dr. D, being the massive jerkoff that he is, decides to take them both out just for the sake of showing off.
-Dr. Doom sends out a message to his foes that he will end them in one weeks time.
-Doom has one week to prep for the fight before initiating the battle himself.
-Goku and Superman have the same week to prepare. They can not attack Doom prematurely, as he has made preparations to keep himself from being found.
-Goku and Superman can do whatever they want with their prep so long as it's in character. (morals ON)
-Doom gets Superman's Comic Vine page and Goku's Anime Vice page. His knowledge will be limited to that.
-Superman and Goku get Doom's CV page.