Rotom, Corsola/Cursola, Sinistea/Polteageist, Drifloon, Litwick, Giratina (either form), or Poltchageist/Sinistcha messing their pamps would be my top picks.
Rotom, Corsola/Cursola, Sinistea/Polteageist, Drifloon, Litwick, Giratina (either form), or Poltchag