I daydream sometimes about "Mortal Kombat vs. DC Universe" instead being "KOF vs. MLP FIM" and the basic story being pretty much the same where Rugal attempts to open a dimensional rift and the warp gate is destroyed by Mai before he can fully pass through it and on the MLP FIM side of the story Tirek having become stronger then before over powers the main 6 to get to one of Celestia's magic mirrors in order to conquer the entirety of the multiverse and realizing there's no way to stop him Twilight shatters the mirror before Tirek can fully pass through it, these 2 separate events cause Rugal and Tirek to fuse together into the being Tirugal which also cause the MLP FIM universe and KOF universe to grind together, the same story plays out as it did in MK vs. DC and at the end where a war brakes out between both sides the 2 left standing are Mai Shiranui and Twilight Sparkle who must now work together to defeat Tirugal
Mai: you don't fight for him
Twilight: neither do you
Tirugal: WHAT ARE YOU DOING?!!!
Mai: then it seems we have a common enemy
Twilight: and a common goal
The 2 of them both manage to break free of Tirugal's mind control and prepare to fight
Tirugal: face each other or face me it makes no difference YOU WILL FIGHT!!!
Tirugal is then defeated and the universes then restored leaving Rugal stranded in the MLP FIM universe and vice versa
Twilight Sparkle: Mai! She's gone, huh? we're in Canterlot.
The main 6 hear a loud grunting as they look over the balcony and see Rugal in pony form
Applejack: who in tarnation are you?!!!
Rugal now declaring himself as ruler of their world as his answer then attempts to throw an energy ball at them then discovers his powers don't work in the MLP FIM universe
Twilight: if you are anything like Tirek you will find no refuge here! Your fate will be decided by Celestia and Luna!
Twilight then tell teleports him and herself off screen and we then cut to him shouting in anger chained up in Tartarus.