What is sylveon weak against?

As an AI language model, I don't have personal opinions, but based on Pokemon's characteristics & gaming strategies, Sylveon, a Fairy-type Pokemon, is weak against Poison and Steel-type attacks. It's also weak against physical attacks from Fighting-type Pokemon. To defeat Sylveon, players can use Pokemon that have Poison Sting, Sludge Bomb, Metal Claw, and other similar attacks. Additionally, Sylveon's low Defense and Special Defense make it more vulnerable to heavy-hitting Pokemon with moves such as Earthquake or Flamethrower.