Genesect

Genesect has a nice niche in Doubles OU as a strong offensive pivot with great coverage that can OHKO prominent threats such as Landorus-T, Tapu Lele, and Mega Salamence. It can also OHKO what is arguably the best Trick Room setter in Diancie while denting others with its STAB U-turn and gaining momentum easily. While Genesect does have a lot going for it, it has a poor matchup against common Fire-types like Mega Charizard Y and Volcanion. Genesect's awkward base 99 Speed means that it's often reliant on a Choice Scarf, which makes Genesect very weak to opposing speed control and also locks it into one move, though it does allow Genesect to outspeed most of the unboosted metagame. Despite having good defenses and a solid typing, Genesect's bulk is surprisingly poor; it even struggles to switch into some resisted moves such as Tapu Lele's Psychic, and being a mixed attacker forces it to run a Hasty or Naive nature, further lowering its bulk. This can be somewhat circumvented by opting for an Assault Vest set, but that leaves Genesect slower than many of the threats it wants to check. Overall, Genesect is a solid choice for teams needing a fast answer to Fairy- and Psychic-types.