>>45861732Bring some ghost types in with you. You can catch them right outside the gym. Her team doesn't carry a lot of priority so any mon with Shadow Sneak becomes a viable revenge killer for half of her team.
Dark types are offensively weakened by the field but defensively they're still solid options. Her team doesn't bring enough coverage to handle them because she's overreliant on the field, so you can chip her out with strong secondary stabs.
Or you can buy Flash from the game corner and completely shut down the field entirely.