Yesss!!! I defeated the E4 and earned the Champion Badge yesterday!!
You want to know my strategy? Ok
1st, stack up many potions (this is more than needed, but just in case!)
-12 full recovers
-8 revives
-5 max elixr
-1 antidiote
My Team (U should ev train them first)
Mewtwo
shiny Mewtwo
Black Tint Slaking
Shiny six aura Gengar
Mega Charizard Y
Darkrai
Vs Lorelei
Mewtwo
1 or 2 clam mind (antdiote when poisoned
spam thunderbolt, aura sphere to mamoswine, weavile and kyruem
Vs Bruno
Mewtwo
psystrike should take care of the first 3
Mega Gengar
Sludge Bomb for Gallade
Mega Charizard Y
Overheat for Lucario
Mewtwo
Psystrike for Keldo
Vs Agatha
Darkrai
Dark pulse should take care of the first three
Slaking
Play rough for spiritomb
Darkrai:
Dark pulse for Gengar and Giratina
Vs Lance
Slaking
spam play rough
Earthquake for Dialga
Vs Gary
Mega Charizard Y
Overheat for Metagross
Slaking
Earthquake for Tyrannitar
Darkrai
Dark pulse for Alakazam
Mewtwo
Aura sphere for Slaking
Mega Charizard Y
Dragon Pulse for Garchomp
Mewtwo and Darkrai
Spam aura sphere and focus blast fpr Arceus
- be careful as Arceus' extreme speed can one shot you
THE END
Good luck!!