(I'll try to answer this but just remember I'm not that good at rating other people's Pokemon/Teams, so anyone please tell me if there's anything wrong.)
Have you tried a dark type move?
I'd say Knock Off is a perfect move for so many reasons. First of all it has decent power, multiplied by 1.5 if the opponent is (I mean, when are they not?) holding an item. Knock Off also knocks off the annoying opponent's annoying items like leftovers. Example; Chansey. This Pokemon is only reason it's better than it's evolution; Blissey is because of Eviolite. Knocking of Eviolite is a big advantage, because now Chansey is now more vulnerable, plus the fact that it might not actually survive getting hit by Knock Off in the first place even with Eviolite because of it's terrible defense stat, Knock Off's increased power, and you have a life orb. Another reason Knock Off is a good move is because it's a dark type move, which provides coverage against Psychic Types, which is one of Hariyama's weaknesses, and Ghost Types, which Hariyama's STAB doesn't affect.
However keep in mind that Hariyama has terrible defense of it's own, plus it's also terrible special defense and speed, so you have to hope that it will survive being attacked before it can attack. Just know which Pokemon you're gonna battle against with this and you'll be fine.
