Rayquaza

Great League:  1 / 5

Research Rayquaza can have a low enough CP to enter the Great League if rerolled via trade, but it really shouldn't be wasted for such things. Competition with Dragons such as Altaria, Dragonite, and Dragonair leaves Rayquaza as largely a gimmick choice.

Ultra League: 2 / 5

Rayquaza's huge attack stat doesn't do it any favors in any restricted-CP format, resulting in poor bulk compared to the rest of the meta. Breaking Swipe may be an excellent move, but Rayquaza still heavily competes with higher stat Dragons like Dragonite and Giratina. Its poor bulk means it won't be able to make great use of Breaking Swipe's debuff.

Master League: 4 / 5

WIthout the CP cap to hold it back, Rayquaza's huge attack is finally an asset rather than a hindrance. The addition of the extremely potent Breaking Swipe gives Rayquaza a tangible niche over the similar Dragonite. Though Rayquaza's bulk is still poor by Master League standards, it is now bulky enough where Breaking Swipe's Attack drops can prove to be irritating. Rayquaza is at its strongest in 2-shield matchups, where it can rack up multiple Attack drops on an opponent. This is most devastating against opponents who rely on Charged Attacks to deal a majority of their damage, such as Excadrill and Mewtwo. Additionally, thanks to Dragon Ascent, Rayquaza can be a devastating closer; the move can pull off impressive feats such as nearly oneshotting Zacian, Xerneas, and Togekiss. Even the extremely tanky Lugia reels to the sheer power of the move.

Despite Breaking Swipe's potency, Rayquaza can find itself still struggling against common Pokemon such as Dialga, Zacian, Xerneas, and Melmetal. Its weakness against common high damage Fast Attacks such as Dragon Breath, Dragon Tail, and to a lesser extent, Charm and Powder Snow make it challenging for Rayquaza to stack Attack drops. Unlike Dragonite, Rayquaza struggles to cleanly dent Steel-type opponents, and may have to rely on committing shields to overcome them.