Best Team: Charizard, Nidoking, Starmie, Jolteon, Dragonite, Bellsprout (HM Slave)
Charizard: Flamethrower, Fly, Dragon Claw, Strength
When you get Charmander it can take on the first gym as it learns Metal Claw to kill the Rock Types. Then, as you come out of Mt. Moon, there is a move tutor that can teach it Mega Kick - For the second Gym. It can defeat these types with its moves: Grass, Ice, Steel, Bug, Fighting and Dragon. It is weak to: Water, Rock and Electric.
Nidoking: Earthquake, Shadow Ball, Megahorn and Rock Slide. Catch a NidoranFemale before you go into Mt. Moon. Then when you take the underground tunnel, trade for a NidoranMale - NidoranMale has better attack, plus from the trade it will gain boosted EXP. It can defeat these types with its moves: Rock, Fire, Steel, Electric, Ghost, Psychic, Dark, Grass, Ice, Flying and Bug. It is weak to: Water, Ice, Psychic and Ground.
Starmie: Surf, Psychic, Ice Beam and Confuse Ray. Catch a Staryu in Verilimon City and evolve it with a Water Stone. Starmie is very fast and has really high special attack. It can defeat these types with its moves: Fire, Rock, Ground, Poison, Fighting, Flying, Dragon and Grass. It is weak to: Electric, Grass, Dark, Ghost and Bug.
Jolteon: Thunderbolt, Thunder, Thunder Wave and Hyper Beam. In Celadon City, in a building, there is an Eevee - evolve it to Jolteon with a Thunder Stone. Jolteon has extremely high special attack and will out speed almost anything. It can defeat these types with its moves: Water and Flying.It is weak to: Ground.
Dragonite: Outrage, Fly, WaterFall, Flamethrower. Catch a Dratini/Dragonair in the Safari Zone. Very powerful. It can defeat these types with its moves: Dragon, Grass, Fighting, Bug, Rock, Ground, Fire, Steel and Ice. It is weak to: Dragon, Ice and Rock.
Bellsprout (HM Slave): Cut, Flash, Sleep Powder, Poison Powder. Bellsprout can use Cut to get you through small trees and Flash for dark caves. You can catch it in Cerulean City.