I'm trying to think of a good team to take on the Battle Tower, but I'm not coming up with that many ideas. Here's what I got so far:
Garchomp w/ Life Orb
Dragon Claw/ Dragon Rush
Fire Fang/ Flamethrower
Stone Edge/ Stealth Rock

Arcanine w/ ???
Flare Blitz
Thunder Fang

Gengar w/ ???
Shadow Ball
Sludge Bomb
Focus Blast

I'm not to sure about natures or who else I should train for this team.