Well if you don´t mind training a new Pokemon I recommend you Venomoth with Quiver Dance. Is pretty usefull in combination with Leech Seed on her Muk. You could also let Toxikroak relearn Mud Bomb and Nasty Plot to set up on her first two Pokemon. Sadly it doesn´t have Dry Skin. You could also try to set up Bulk up with Blaziken as soon as her Tentacruel is down and she has something other than Nidoqueen and Dragalge (Dragon tail) out. You could also try setting up Calm Mind with Guardevoir but I doubt she would survive a double Sludge Wave from her first two Pokemon.
Edit:
Oh yeah, appearently Magneton is also pretty good against her.