Last gen many good players were putting HP Grass on Honchrow as a "filler move" to surprise Rhyperior (their moveset was Brave Bird/Sucker Punch/Superpower/HP Grass). Though i doubt that this would fix the main problem; sure, you KO Rhyperior, but you're still walled by steel pokes. With Moxie, of course, since it lacks Superpower.
M-BLADE: Saying nonsense since 1988.
Owner of the best signatures ever. Ditto.