Here is a good team you can use for the Elite Four and Cynthia in Pokemon Diamond, Pearl, and Platinum:
Uxie at level 80
Mismagius at level 65
Rapidash at level 62
Torterra at level 60
Palkia/Dialga at level 68
Staraptor at level 60
or...
Rapidash at level 62
Luxray at level 65
Empoleon at level 63
Lucario at level 63
Crobat at level 67
Golem at level 64
you should have a stoutland lvl. 55, a samurott who knows surf lvl.60 a durant lvl.50 a basculin who knows surf lvl.49 a bisharp lvl.60 and a krookodile lvl.57.
note: fighting,electric and normal type moves wont work on ghost types. bottom left corner is ghost, top left is ground, top right is psycic, and bottom right is fighting.
yes swarpert is a greatest Pokemon to defeat elite four
Fire and water are the best combination to beat the elite 4.
I would suggest fighting the elite four with a water, fire, ice, rock, electric, and fighting type pokemon.
Wailord
red or the elite four if you beat red the elite four Pokemon will be jacked up or red again after you beat the elite four his Pokemon are the same levels as before
The elite four
battle the elite four
Elite Four Sidney/Sydney: Uses Dark Pokemon Elite Four Phoebe: Uses Ghost Pokemon Elite Four Glacia: Uses Ice Pokemon Elite Four Drake: Uses Dragon Pokemon Champion Steven: Uses mostly Steel & Rock Pokemon.
elite four again and again.worked for me
Crystal is suicune but im not sure of the rest. Emerald it's rayquazza. he can beat the entire elite four by himself.
The best way to defeat them is to train your Pokemon. No Pokemon will be above level 50 or something like that. The 4 main elite four, their Pokemon are only in their forties.
The best levels to have are 60 or above Pokemon wise i doesn't matter the easiest way to beat the elite four is train Pokemon that defeat each members Pokemon.