Critical captures are exactly like critical hits—they're quite powerful, and happen when you least expect it. So far, I've had two critical captures, but none were on Yveltal. I was required to catch Yveltal the old-fashioned way—weaken, paralyze or make it fall asleep, and throw dozens of Ultra Balls. To be honest, Yveltal was one of the toughest legendaries I've ever faced in any Pokémon game. I've had to reset my game for about eight to nine times before finally having it captured. At that time I was battling it, all of my Pokémon were six - nine levels higher, but somehow, it still managed to take them all out without any trouble. The strongest Pokémon I had on my team was Blastoise, as its defensive stats were extremely high. And when it transformed itself into its mega form, its defenses were raised even higher. For Yveltal, though, it was no hard task to have this Pokémon defeated. With a single Oblivion Wing, it was able to make it faint in an instant. d: