Huge weakness to Ground/Rock/Water with DroughTales AND Shanderaa. Hippowdon will just laugh at you as it sets up Stealth Rock AND changes the weather meaning that in order to use a 1 turn boost Solarbeam you need to switch to something, then BACK to DroughTales to make the weather sunny, then to Shanderaa. Shanderaa COULD trap Hippowdon with Shadow Tag but does it REALLY want to do that when it doesn't have Levitate and Hippowdon carries EQ on virtually every set?
Not much of a difference with Tyranitar/DrizzleToad.
I'd like to point out you don't have to start with a weather changer on a team and I said the moveset is gimmicky sounding.