getting there is easy, beating her is the hard part.
She has Meditite lvl 27
machoke lvl 27
and lucario lvl 30
The most effective would be Flying, ghost, and fire.
If you started out with Chimchar then great, lvl him up to about 35.
I used that turtle thing, ponyta, Staravia, gyrados, ghastly (which did nothing but die), and jolteon.
I found electric very effective against machoke and meditite, and took all the others to take out lucario. all of my pokemon were lvl 30