TEW vs. WMMA
Simple really. Stick both games together. You could have a WMMA career game mode or a TEW career game mode. Another thing could be is, you could buy the license to play a WMMA or TEW career only. Or then you could buy a license(probably twice as dear) to play either or the blended mode.
The blended mode would incorporate both game features and you would have the option to run a wrestling fed or an mma fed. You could ofcourse switch over to the other profession mid game. And could sign mma guys to your wrestling promotion and sign wrestlers to your mma promotion.