Question: how to beat the elite four in pokemon diamond easily?
Answer: Try buying 'moomoo milk' because it's cheaper than potions and heals more than super potions. If you want to beat the Elite Four, you need a good team. Have Infernape, Mamoswine, Gyrados, Garchomp, Roserade (Make sure it stays as a Roselia until Lvl 40 to learn the move Petal Dance) and finally a Raichu or a Luxray.