What types do the Elite Four and Champion use, I have my 7th badge and am starting to think about what team I'm taking with me.
The Champion has a well made team with attacks that can type-trump the pokemon you use to type-trump. For example, she has a Milotic that will use ice beam against a grass type. I just worked my way back to her with the level 70s I caught and some I got from Ruby like Lugia and Ho-oh from whatever island it was you go to. So here is what she has:
Spritomb [Ghost/Dark]: Level 61
Bring someone that knows toxic. I also used my Roserade's Toxic Spike so all of her pokemon were poisoned upon entering the fight. Now, this is weak to NOTHING, so just use strong attacks.
Roserade [Grass/Poison]: Level 60
Easy to take down with so many weaknesses.
Gastrodon [Water/Ground]: 60
Obviously grass is a heavy hitter here, and hopefully your grass type also has poison type because Gastrodon can hit a pure grass type hard with sludge bomb.
Lucario [Fighting/Steel]: Level 63
I, personally, found my Infernape's Flame Wheel quite effective here. It's easier to hit it wh a physical fire attack because it has high special defense.
Milotic [Water]: Level 63
Milotic hits grass types hard with ice beam, so it's better to use Electric. If you don't have electric, use another pokemon to drain all of it's attacks down, then trump it with grass.
Garchomp [Dragon/Ground]: Level 66
Ice attacks will work wonders against this big guy. My level 50 Empoleon needed only two ice beams to take it out.
The champion is no easy battle. With four Full Restores, as all champions have, the battle can drag out. The Elite Four aren't so easy this time around either. I was a bit surprised by the first one. If you want to know about them, just let me know and i'll post some info.