Hydreigon

Hydreigon's high Special Attack and wide movepool give it unique power to punch holes by threatening common defensive Pokemon such as Slowking, Heatran, and defensive Landorus-T. This is further complemented by its decent Speed allowing it to outpace common offensive Pokemon such as offensive Landorus-T, Urshifu-R, and Tapu Lele. On top of all this, Hydreigon's defensive typing, ability, and Roost let it check Heatran extremely effectively and come in on slower defensive Pokemon such as Toxapex and Slowking with ease. However, although Hydreigon has passable Speed, it is still outpaced and OHKOed by common Pokemon such as Dragapult, Weavile, and Tapu Koko. It will also often be checked by some Pokemon such as Fairy-types, which it struggles to break through without Flash Cannon, and Blissey, which it can't do much to without Nasty Plot boosts.