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Why the fuck does Aura Break even exist? All it does is make Xerneas and Yveltal deal 25% less damage instead of 33% more. You can't even use it on the best form of Zygarde, and the other 2 forms have stats so far below Xerneas and Yveltal that you'd never want to use it in any format with them.
Game Freak had to give Zygarde one of the most broken moves in Pokemon for it to stop being completely outclassed by Garchomp, and Garchomp isn't even a legendary. Zygarde basically plays with no ability to make up for having Thousand Arrows.