The Pokemon Black and White Elite Four Guide guide explains a very effective way to defeat the Pokemon in the Elite Four. This is for the first time that you are facing them and not the second. I recommend that you have above level fifty Pokemon and have lots of revives and full restores with you, this is going to be a tough battle. As annoying as they are, all trainers will use Full-Restores on their Pokemon if it is on low health so get ready to injure it many times. Once you enter the Elite Four you should see some stairs. Going from left to right are the trainers Shauntal, Grimsley, Caitlin and Marshal. Please note that you will not have to defeat the Elite Four leader the first time round but you do have to defeat N and Ghetsis, so be ready.
Shauntal is up first. She mostly has Ghost-type Pokemon and uses Dark-type moves. Her Pokemon are: Cofagrigus, Chandelure, Golurk and Jellicent. Use ghost-type, dark-type and water-type moves to defeat this trainer. Cofagrigus knows the move Shadow Ball which deals big damage so watch out. It is weak to ghost-type and dark-type moves. Chandelure knows the dangerous move Fire Blast so be careful. Its weaknesses include; water, ground, rock, ghost and dark, so you have a lot of options. Next is Golurk with his mighty move Earthquake. He is weak to water, grass, ice, ghost and dark-type moves. Finally, Jellicent is used. It knows Surf which is super-effective against fire or ground-type Pokemon. Defeat this Pokemon with grass, electric, ghost or dark-type moves.
Grimsley is second. His Pokemon are: Scrafty, Krookodile, Bisharp and Liepard. Use fighting-type moves to give you the edge. Scrafty knows the move Brick Break and is weak to fighting and flying-type moves. Krookodile knows the powerful move Earthquake but is weak against water, grass, ice, fighting and bug-type moves. Bisharp knows the move Aerial Ace and is weak to fighting, fire and ground-type moves. Liepard knows the move attract and is a female so use a male Pokemon if you have one. It is weak to fighting and bug-type moves.
Caitlin is next. Her Pokemon include; Reuniclus, Musharna, Sigilyph and Gothitelle. Reuniclus knows the move Psychic and is weak to bug, ghost and dark-type moves. Musharna knows Charge Beam but is weak against bug, ghost and dark-type moves too. Sigilyph knows the move Air Slash and is weak to electric, ice, rock, ghost and dark-type moves. Lastly, Gothitelle knows Shadow Ball and is weak against bug, ghost and dark-type moves.
Finally, you should face off against Marshal. Marshal has the Pokemon; Throh, Sawk, Mienshao and Conkeldurr. Throh knows the move Bulldoze and its weaknesses are fighting and psychic-type moves. Sawk knows Stone Edge and is also weak to fighting and psychic-type moves. Mienshao knows the move Jump Kick and Conkeldurr knows Hammer Arm. They are both, like the others, weak to fighting and psychic-type moves.