I´d suggest a team like
Charizard lvl 60 against the elite 4 and lvl 85/90 after that with FLY EARTHQUAKE FLAMETHROWER and BLAST BURN
then (with cheats)
Venasaur same lvl as charizard with HIDDEN POWER (fire) SOLARBEAM FRENZY PLANT and GIGADRAIN
Blastoise same lvl as charizard with SURF HYDRO CANNON ICE BEAM TOXIC
A Snorlax around lvl 55 against elite 4 and 80 after with SHADOW BALL (it will help against e4) HYPERBEAM YAWN/SLEEPPOWDER/HYPNOSIS and DREAM EATER
RAICHU (or pikachu, if you wanna be like trainer red) lvl 65 against e4 and 90/95 after. with THUNDER THUNDERBOLT IRON TAIL and your choice (maybe SLAM, learned lvl 20 by levelup)
finally, catch an Abra (use mean look to prevent escape) go through digletts cave and trade for a mr mime in the house below on route 2. teach it SECRET POWER BRICK BREAK REFLECT and PSYCHIC same lvl as snorlax. INCREDIBLE sp. attack and sp. defense. but id suggest using HP UPS and carbos (i think) or whichever one raises regular defense.