Umm R/S battle tower sucks ***. Use a Heracross and a Starmie and your set pretty much
Heracross @ SHell Bell
Brick Break
Mega Horn
Earthquake
Rock Slide
Starmie @ Shell Bell
Surf
Thunder Bolt
Ice Beam
Psychic
Thats what I used and i got through it with ease but be sure to carry a Pokemon that can take a hit just incase you find yourself in a sticky situation. My back-up pokemon was always
Umbreon @ Leftovers
Moonlight
Mean Look
Toxic
Double Team
That team swept through the Battle Tower with relative ease for me