Scorpion VS Sub-Zero: 3-7
We've seen Sub-Zero evolve as a character throughout the series while Scorpion has been stuck in the same place since game one, which I believe that in a realistic 101 between the two, Sub-Zero will use his experience to gain the upper hand. Scorpion hasn't really evolved at all, and Sub-Zero generally seem like the more intelligent one of the two, not to mention he grows more and more powerful, so I believe he will come out on top.
Ermac VS Quan Chi: 4-6
Ermac has the power of a thousand souls, two of them being King Jerrod and Shao Kahn, which are both rather powerful characters, but he is an unstable individual who needs to charge up now and then. Without a source of soul energy, Ermac would quickly become weaker, so he would end up losing to Quan Chi's power and experience. However, Quan Chi is also arrogant, so I can see him underestimate Ermac at the beginning which will make him lose a couple of fights before he put some real effort into defeating Ermac.
Johnny Cage VS Goro: 2-8
Both of them are rather arrogant, but in the end, Goro has an immense strength and alot more experience that Johnny. Goro killed several Earthrealm champions before he met Liu Kang, and even killed the legendary Great Kung Lao, so I doubt Johnny would get far against Goro. The Prince of Pain will surely win this one.
(Note: the movie isn't canon)
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Kitana VS Kung Lao: 6-4
Kitana is a 10.000 year old assassin who have probably killed millions of people in her lifetime. Kung Lao will be a mighty foe, but I believe Kitana will gain the upper hand and win the battle.
Sonya VS Mileena: 4-6
Though Mileena has the body and fighting capabilities of Kitana along with the ruthlessness and bloodthirst of a Tarkatan, she is still very "young" and unpredictable. And Sonya is a tough badass chick, so I can imagine these two being very equal when going toe-to-toe, but I believe Mileena will end up the winner.
Kano VS Reptile: 5-5
Two henchmen known to take a beating every second they are on the screen. There's a reason Reptile has survived as long he has though, and his acid could melt through Kano's cybernetics. Kano is also very arrogant and known to taunt his opponent, but in the end he always gets the boot.