I've only faced her on one playthrough, and... it was definitely a challenge. I remember I had to level up my Pokemon a lot, and iirc I did make use of SR and I'm pretty sure I relied a lot on Moxie @ Scrafty and Regenerator @ Audino, while Herdier on the other hand, was useless. I think the biggest challenge was Braviary, iirc, but the Rocky Helmet really helped. XD;
But yeah she's definitely tough to beat if you're just using your favourites times like this are when I wish I had better favourites.