Hydreigon

Hydreigon is a devastatingly powerful wallbreaker in UU due to its incredible Special Attack, great movepool, and excellent STAB combination. Its Choice Specs set has no reliable switch-ins apart from Primarina and Chansey, ripping apart common defensive staples like Amoonguss, Scizor, and Hippowdon. Hydreigon also can utilize a Choice Scarf set to revenge kill setup sweepers and fast threats, like Gyarados, Zygarde-10%, and Azelf, while also having a fast U-turn to escape unfavorable matchups and potentially Defog to compress entry hazard removal. Hydreigon's decent defensive typing alongside recovery in Roost lets it naturally check threats like Slowking, Rotom-W, and Chandelure. However, Choice Specs Hydreigon has an exploitable Speed tier, falling short of staples like Salamence, Thundurus-T, Keldeo, and Cobalion, which allows it to be revenge killed rather easily. On the other hand, the Choice Scarf set lacks the outright power to get past Hippowdon, Mandibuzz, and Celesteela, and it also can get heavily punished for locking into any move, with more offensive teams outright using it as setup bait. The presence of Fairy-types that are neutral to Flash Cannon like Primarina and Azumarill means Hydreigon can struggle to click a nuclear Draco Meteor when they're on the enemy team. Moreover, it suffers from four-moveslot syndrome, as it has to choose between Flamethrower to cook Celesteela, Cobalion, and bulky Scizor or Flash Cannon to keep the aforementioned Fairy-types and Togekiss from blanking it.