pokemon is not important, the moves and your tachics are very important.

you should at least have your pokemon at lv50

evolve haunter and grow crobat a few levels so that you can use him with the first
trainer.

Cynthia's Milotic can wipe out Torterra(Ice Beam) Giratina(Ice Beam) Piloswine(Surf)
Crobat(Ice Beam) and Rhydon(Surf)
Get a water pokemon with you (such as Gyarados or something like that)

well i think you could win just get lots of those things that restore your pp

I spent ALL my $(seriously all) for 30 Max potions, 30 Full Heals, 20 Revives and the rest
for Full Restores.
After every battle i fully healed my pokemon and saved.
I think that's the only way to win (except getting Lvl 100s from friends).

rayquaza lv.90
groudon lv.90
garchomp lv. 95
cresselia lv. 100
regigigas lv.100
girantina lv.100
50x full restore, revive,and revival herb

I can wipe out rayquaza, garchomp, groudon and giratina only with my milotic. You really
need Ice resistance...

you honestly think that team is gonna defeat the ellite four, thats a bunch of the crapest
trained pokemon ive ever seen to face them. theres this new thing its called TRAINING!!
i battered the ellite four with:
torterra lv81
salamence lv100
mewtwo lv100
lugia lv100
regirock lv100
deoxys lv100

Don't you think that's a little unfair to transfer pokemon from other games to beat
them???