How do you catch genasect in white?

To catch Genesect in Pokémon White, you need to first acquire the event item called the "Genesect Download." This event was typically distributed via special promotions, so ensure you have the necessary event or item. Once you have access to the area where Genesect appears, usually the Pokémon League or a designated location, approach it and engage in battle. Use status effects, like Sleep or Paralysis, and weaken it to increase your chances of capturing it with Ultra Balls or other high-capture-rate Poké Balls.