• Goku (Super Saiyan God Super Saiyan)
  
• Madara Uchiha (Rinne Sharingan & Dual Rinnegan)
  

Pre-Knowledge:

• Neither combatants have any knowledge of the other prior to the fight.
  

Location:

• Outer-Space. (More specifically, the void between galaxies.) 
  

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I'd say that Madara wins this, fairly easily too. The reasons are simple. First of all, Madara is immortal and the only way to beat him is to seal him with jutsu, something Goku cannot do. The other  thing is that Madara possesses whats known as Creation of All Things which is a jutsu that allows the user to create anything from nothingness. (Efficiently being a God.)  Madara also possess several Limbo clones which can only be sensed or seen by those who possess Rikudou Chakra, and each clone is nearly as power as himself. On top of that he possess the Rinne Sharingan and even though he never used it, Kaguya did and displayed powers that were beyond that of any human being, capable of instantly trapping and controlling individuals as well as changing dimensions in an instant. (Taking others with her.)