I know most people already know, Xernas would win and that is true. Also Zygarde would lose to Xernas. I know that not all games have equal legendaries, like Palkia and Dialga. In my opinion Dialga would one hit ko Palkia with Roar of time. That isnt this though. There is no point in Yveltal and Zygarde if Xernas can wipe them out that easily.