Mew

Mew is unique among Psychic-types in BW OU, running a fully defensive set with Will-O-Wisp to cripple common answers such as Tyranitar, Ferrothorn, Excadrill, Scizor, and specially defensive Skarmory rather than breaking through them with coverage. Its typing, bulk, and instant recovery make it a solid answer to opposing Psychic- and Fighting-types; Mew walls Alakazam and Reuniclus should they lack Shadow Ball or Signal Beam, can shut down Technician Breloom and Terrakion should it not switch into their boosted coverage, and additionally can survive most unboosted attacks from physical threats such as Dragonite, Garchomp, Excadrill, and Mamoswine. Mew has Taunt and theoretically limitless coverage to cripple Ferrothorn and Tentacruel, as well as taking advantage of Reuniclus, Poison Heal Gliscor, and Poison Heal Breloom, which typically shrug off burns.

Mew is quite niche in the current metagame for numerous reasons—its inability to do anything to dangerous Fire-types such as Heatran and Volcarona, its extreme vulnerability to status, and its general lack of offensive utility compared to other Psychic-types such as Alakazam, Reuniclus, and Latios. Heatran gets a Flash Fire boost from Will-O-Wisp and threatens to heavily damage Mew, and Volcarona often outspeeds Mew and threatens to sweep with Quiver Dance while OHKOing with a boosted Bug Buzz. Mew also is deathly afraid of any status despite Synchronize statusing the foe—Toxic and burn greatly decrease its longevity, while paralysis stops it from using its Speed to prevent setup. Mew often relies on its Speed and Roost to survive foes rather than resistances or raw numerical bulk—therefore, it especially struggles against rain teams, as the secondary effects of Scald and Thunder often let strong sweepers such as Keldeo, Latios, and Thundurus-T 2HKO it. Mew is generally outclassed by Jellicent, which shares the same moveset while having a far better typing and Water Absorb to and block Rapid Spin and check Keldeo better despite Mew's superior Speed and better ability to check Psychic-types. Mew is also hard to fit on teams compared to other Psychic-types given of its lack of resistances and offensive utility.