And the Arceus said to some random guy,
Over-level thy Pokémon.
And some random guy beat the E4.
Just kidding :D If you want a serious strategy, try this: Outspeed that blasted soul-sucker and smite him upon the astral plane.
After running Ice, Fire, and Electric through the site's Type Coverage Checker, there is a grand total of one. Guess who it is?
Oven Buster (Rotom-Heat)@ Lum Berry
Ability: Levitate
- Shadow Ball
- Will-o-Wisp
- Charge Beam
- Overheat
Yay! Rotom! Fire/Electric resists all three of Ice Punch, Fire Punch and Thunder Punch, while Shadow Ball nails each and every one of Phoebe's Pokémon bar Sableye. Will-o-Wisp reduces the damage done by Dusknoir to the rest of you Pokémon should Oven Buster fall. Charge Beam has a chance of boosting your Sp. Attack, and Overheat is a nuke. The recommended item is Lum Berry because Dusknoir also carries Hex. This is a problem because both of her Banette will try to status you, and you don't want to by KOed by an unlucky Toxic + Hex.
How does Rotom fare against the rest of the Elite 4?
Sidney
Mightyena: Neutral
Shiftry: Overheat
Cacturne: Overheat
Sharpedo: Aqua Jet!
Absol: Neutral
Glacia
Glalie: Overheat
Froslass: Shadow Ball
Glalie: Overheat
Froslass: Shadow Ball
Walrein: Charge Beam
Drake
Altaria: Neutral
Flygon: Rock Slide!
Kingra: Surf!
Flygon: Rock Slide!
Salamence: Neutral
Stephen
Skarmory: Overheat
Claydol: Neutral
Aggron: Stone Edge!
Cradily: Ancient Power!
Mega Metagross: Overheat
Good luck defeating Phoebe!