Lmfao Kotal is a strong enough fighter in his own right don't get me wrong, but he's no Shao Kahn. They're on different levels and they're Kahns for different reasons. Kotal is a Kahn because he's a good leader, Shao is a Kahn because people fear his strength.
Kotal's out here getting mopped by Jacqui and Kung Jin. The same Jacqui/Kung Jin getting they asses rocked by Sub-Zero and Kitana. Kotal's strength was made clear when he was shown to be shit-scared of Shinnok. A battle between these two would be epic just to see how badly Shao mollywhops Kotal's ass and how much shit talking he does in the process
History really does go to show that Shao Kahn would probably body a lot of people, but that's not the point. I mean Raiden had to call on the Elder Gods to destroy him forever because otherwise he would just come back again stronger and literally destroy all the realms.
The point is to hear the trash talk and see a big fight between Emperors, the victor of said fight or "who's stronger" are things not nearly as interesting as what's going to preceed them. At least that's what I think.
I hope Kotal Kahn and Shao Kahn don't meet in battle. Kotal is a great character and other than Kung Jin beating him I was generally impressed by how he was handled in MKX story. Shao Kahn is pretty much the strongest character in the MK universe so isn't going to job for anyone. Liu Kang beating him is more of a set piece. But a character like Kotal has no business going up against him.
Hence why I used quotations. ;P
But thing is, he made that clone because he knew he was being incredibly weakened from the war, so he didn't want to risk actually dying. And with no Shinnok or Quan Chi to rely on reviving him, he hid in the shadows while his clone sat on the throne.
But clone or not, that was still a Shao Kahn they killed.