Pls Omastar offensively is way superior to Gore, it has more weaknesses but iirc ground/fight types arent really seen much in NU and it has better setup opportunity vs normal spam. Theres also the fact Omastar can perform more roles like being a bulky spiker in a tier where we lack decent spinners and all of them just get shredded by a stab surf except maybe sp def hitmonchan or something, which is not really worth running outside of spinning vs omastar.
And Poliwrath really cant switch vs stab returns that well, it sure wouldnt be my 1st option to try stopping bull.