Well Xerneas was ridiculously easy to catch, for a moment I was thinking of using the master ball but I decided to try with other balls first, thank god I didn't use the master ball, I caught it on my second throw with an ultra ball.
And FINALLY a boss battle where I had to restart, I refused to use Xerneas and that's probably the reason I had a hard time for the first time in this game, that Mega Gyrados is lethal.
Nintendo and PC gamer