How do you defeat the elite four in Pokemon diamond?

You bring different types of Pokemon. The way i beat the Elite Four is: the first trainer is a bug lover, so I used flying Pokemon. the second trainer is a ground lover so i used a water type. the third is a dude who loves fire so use a water type Pokemon. the last is a psy. user i used electric, flying, and water. the champ I used a flying type, she has different types of Pokemon so u can use whatever comes naturally. My Pokemon were 60 and above so it was kind of easy for me. Make sure you get a lot of revives and potions.