How do you defest the elite four and the champion on Pokemon Diamond?

I have a level 72 Infernape that knows Ember, Flame Wheel, Rock Climb and Rock Smash, a level 50 Uxie that knows Yawn, Confusion, Future Sight and Amnesia, a level 57 Azelf that knows Confusion, Charge Beam, Future Sight and Psychic, a level 50 Mesprit that knows Confusion, Future Sight, Imprison and Rest, a level 44 Onyx that knows Rock Polish, Dragon Breath, Iron Tail and Sand Tomb and a level 42 Bronzong that knows Iron Defense, Safe Gaurd, Block and Gyro Ball but I keep losing. I need a lot of help.