Apocalypse or Professor X

Definitely so many people still doesn't know about the use & playstyle of professor x
But if someone is talking about synergy then, I think if apocalypse & professor x both came together in same team then it will be next level thing
Apocalypse (as a student of professor x) will get 100% more special attack bonus,
Horseman will get 150% more special damage and many different types of bonuses according other mutant teammates

Kerneas

The feeling of being an absolute unsz'toppable force in giant armor is better for me than mindcontrolling pink constructs