Gyarados

Gyarados is one of the most dangerous setup sweepers in UU due to its fantastic coverage and combination of Dragon Dance and Moxie, which allow it to muscle through almost everything in the tier. Great coverage moves like Ice Fang help it break through Grass- and Dragon-types like Zarude, Amoonguss, and Salamence, while Power Whip allows it to hit Water-types like Rotom-W, Swampert, and Slowking, and beat standard Unaware walls like Quagsire, unlike many other physical sweepers like Azumarill. It has good HP and respectable bulk, allowing it to withstand attacks from threats like Keldeo, Scizor, and certain Excadrill sets while setting up. Unfortunately, its only Flying-type STAB move is Bounce, which has low accuracy and is exploitable because it requires two turns to use without Power Herb. Meanwhile, Ice Fang's power can be underwhelming at times when facing bulky Grass-types like Amoonguss and Tangrowth. Unboosted Gyarados is outsped by many common threats such as Thundurus-T, Zarude, and Nihilego. Even at +1 Speed, it will still get outsped by Choice Scarf users like Zarude and Hydreigon. Gyarados's weakness to Stealth Rock and vulnerable Speed can keep it from safely setting up against more offensive teams. Gyarados struggles against defensive Pokemon like Umbreon, Mandibuzz, Skarmory, and Tangrowth due to their immense bulk and ability to hinder Gyarados from gaining too many boosts.