Crouch so you're low to the ground and minimize the amount of area she can hit you. By doing so, remarkably little of her moves actually hit you, including her dash attack, jabs, grab, and any sort of rising aerial. It also makes her have to aim her float aerials and turnips in a more narrow area, which means they'll be easier to avoid and more obvious.
If she sits there and crouches, you can bait her D-smash and grab her, or space your Bair.
Though it seems like a good idea to just lob Bairs at her, you have to be somewhat reserved because you have no aerial mobility and she spends a lot of time moving back and waiting for you to miss so she can run under you and do SH Nairs, dash attacks, and FC Nairs. Or she might just move back and space Fair and beat it outright. Lots of stuff works.
In general, use your movement and try to keep yourself from being trapped in bad situations. Don't get desperate to hit her, and stay as safe as possible.