Poke Team

Ok you should add Mismagius, Luxray & Rapidash. Make sure they have all have the moves of there types. If you can get an infernape this will be an a great advantage. Also get rid of Lucario & add an strong grass type which it strong & won't die easily. I am glad to help.

~Twilight_Sasuke~

Use a fire type, like Rapidash. Maybe a Roserade would help that team, and top it off with a Drifblim or a psychic type pokemon. Bring lots of potions and revives!

Well, if you insist on using those three...

Include a Roselia (or a Roserade), Sneasel (or Weavile), and Rapidash.

Use Rapidash and Rampardos against the first Elite Four member, who uses bug Pokemon (use Rapidash against them), and a dark/poisin Pokemon who's only weak to ground (so obviously, use Rampardos against them).

Use Roserade against the second member. She uses all ground, rock, and water pokemon; all of which Roserade is strong against.

Use Rampardos, Empoleon, and Lucario for the third member. He uses fire Pokemon (so use Rampardos or Empoleon), along with a Drifblim (again, use Rampardos), Steelix, and Lopunny (use Lucario for those two).

Use Weavile for the last member. He uses all psychic Pokemon, and using Faint Attack (or Night Slash) could kill every Pokemon he has.

And for the Champion, use all you got. The only Pokemon you might have trouble with would be Spiritomb; just use Weavile against him. She also has a Garchomp, Milotic, Gastrodon, Roserade, and Lucario.

Try your best. Bring some Full Restores and Revives, just in case. If possible, some Ethers and/or Elixers could be useful.

If Its your first time I suggest bringing good fire types. Aarons bug times are no match for a Rapidash and Flint's steelix and Lucian's Brongzon are no match either. With the other 2 you should be good!

I used Gyarados, Dialga, Garchomp, Mesprit, Golbat and Torterra for the elite four...
Gyarados - surf, waterfall, dragon dance, dark pulse
Dialga - Acient power, Roar of Time, Dragon Claw, Metal Claw
Garchomp - dragon claw, dragon pulse, dragon rush, fire blast
Mesprit - extrasensory, thunder, shadow ball, psychic
Golbat - fly, air slash, poison fang, sludge bomb
Torterra - earthquake, crunch, solar beam, strength

I used golbat/torterra/garchomp for the bugs...
Gyarados/mesrpit for the ground...
Gyarados/garchomp for the fire...
And gyarados/mesprit/garchomp for the psychic...on the boss I used just about all...if Garchomp (66) is giving trouble it's best to have a dragon/ice with you, if you use those 3 id say to add a gyarados if you can, take away lucario and add a fire or flying (fire is best cause of his last [63]) a psyhic and electric...that would leave gyarados, fire/flying (rapidash/staraptor), pyhicic(legendaries/alekazam/mr.mime)electric (raichu/whiscash..) and your empoleon, rampardos

I don't know rampardos or lucarios stats I havent gotten the rampardos yet and didnt like lucario much so it would be you're choice on wich would be best (stats)