How do you defeat the elite four in Pokemon Platinum?

Take out Staraptor's Wing Attack and give it Close Combat. Get a Heart Scale. Flareon, give it Dig, take out Fire Spin. Empoleon, get it to Lv55-60, take out Cut at the Move Deleter in Cave and teach it Flash Cannon. Delete Whirlpool and give it Ice Beam or Blizzard. Steelix, train it to Lv55-60, take out Curse and give it Earthquake. Take out Rock Polish and teach him Iron Tail. Tropius, train it to Lv55-60.