Necrozma

Necrozma is one of the most powerful attackers in Doubles OU, threatening to 2HKO the entire tier with Expanding Force under Psychic Terrain at +1, which it can easily get to with the combination of Power Herb and Meteor Beam. With many common Psychic-resistant and -immune Pokemon in the metagame such as Heatran and Incineroar folding to its coverage options like Earth Power and Meteor Beam, Necrozma can easily plow through teams once if it gets the necessary support. It fits best of on hyper offense builds where the goal is to win games in as few turns as possible. Psychic Terrain support, which powers up Expanding Force and blocks priority, is critical to Necrozma's success, making either Tapu Lele or Indeedee-F mandatory teammates. Pokemon that can break through Steel- and Dark-types such as Urshifu-R and Heatran also make excellent partners, enabling Necrozma to keep using Expanding Force without worry. While Necrozma can end games once it gets going, it can be slowed down in multiple ways. Rillaboom and Tapu Fini can reliably switch in multiple times and reset Terrain, which heavily weakens Expanding Force, with the former also threatening Necrozma with Fake Out. Opposing Tailwind setters such as Zapdos and Mew also work well against it, as well as other forms of speed control users such as Icy Wind Kyurem-B and Trick Room Diancie. Additionally, while Pokemon such as Incineroar, Heatran, and Metagross must fear Necrozma's coverage, they can all switch into Expanding Force and slow it down.