How do I beat the elite 4 in pokemon platinum?

Here, I will list my pokemon, their moves, and their level. (Please say if i should get a different pokmon or if it needs different moves and what level the pokmon should be): Infernape Lv. 71: Fire blast, Flame wheel, Mach punch and Rock smash.Giratina Lv. 47: Ominous wind, Ancient power, Dragon claw, and Shadow force. Vaporeon Lv. 26: Water gun, Surf, Waterfall, and Brine. Staraptor Lv. 41: Wing attack, Aerial ace, Fly, and Defog. Mesprit Lv.52: Swift, Lucky chant, Future sight, and Extrasensory. I have one extra space for a pokemon so tell me which pokemon that one should be(Include level and moves). Also, Please tell me which pokemon I should use on who (ex. Infernape on Aron or Vaporeon on Flint) THANK YOU FOR ANSWERING!!!