Brock-Pewter City`s Gym Leader
Brock uses Rock-type Pokémon.
His two Pokémon are:
Geodude Level 12
Onix Level 14

To Beat Him use Water Or Grass pokemon NO FIRE POKEMON

Prize: Boulderbadge

Misty-Cerulean City`s Gym Leader
Misty uses Water-type Pokémon.
Her two Pokémon are:
Staryu Level 18
Starmie Level 21
Grass Pokemon Or Electric NO ROCK

Prize:TM 11 & Casadebadge.

Lt. Surge-Vermilion City`s Gym Leader
Lt. Surge uses Electric-type Pokémon.
His three Pokémon are:
Voltorb Level 21
Pikachu Level 18
Raichu Level 24

Use Rock Pokemon NO FLYING POKEMON
Prize: Thunderbadge & TM 24

Erika-Celadon City`s Gym Leader
Erika uses Grass-type Pokémon.
Her three Pokémon are:
Victreebell Level 29
Tangela Level 24
Vileplume Level 29

Have a pokemon with its speed real high she can attack up to 5 time in a row.You should use Fire Pokemon NO WATER POKEMON

Sabrina-Saffron City`s Gym Leader
Sabrina uses Psychic-type Pokémon.
Her four Pokémon are:
Kadabra Level 38
Mr. Mime Level 37
Venomoth Level 38
Alakazam Level 43

Use Ghost Pokemon

Prize:TM 46 & Marshbadge

Koga-Fuchsia City`s Gym Leader
Koga uses Poison-type Pokémon.
His four Pokémon are:
Koffing Level 37
Muk Level 39
Koffing Level 37
Weezing Level 43

Prize:Soul Badge & TM 06.

Blaine-Cinnabar City`s G Gym Leader
Blaine uses Fire-type Pokémon.
His four Pokémon are:
Growlithe Level 42
Ponyta Level 40
Rapidash Level 42
Arcanine Level 47

Your best bet would be useing water pokemon No Grass Grass burns

Prize:Volcanobadge & TM 38.

Giovanni-Viridian City`s Gym Leader
Giovanni uses Ground- and Rock-type Pokémon.
His five Pokémon are:
Rhyhorn Level 45
Dugtrio Level 42
Nidoqueen Level 43
Nidoking Level 45
Rhydon Level 50

Your best bet against Giovanni is Water-, Grass-, or Ice-types

Prize: Earth Badge & TM 27.