>>22334501OU is entirely unplayable as is. My theory is that there are too many OP Megas that are impossible to account for with just a team of 6. Like you can build a solid ass team that's weak to something like M-Pinsir or even M-Houndoom which got popular with the advent of M-Sableye.
If third version Gen VI has anymore OP megas, the inevitable power creep, and possibly but hopefully not speed creep toward the 115 or even 120 speed tier, I'm abandoning all hope for OU at that time.
There's just no way to check all these monsters when you're limited to one Mega each team. You WILL find yourself incredibly weak to at least one Mega, more like 2 or even 3 Megas unless you're a flawless teambuilder.