You go to Pewter City. If you can't get there yet, try fighting some of the other gyms first.
you beat the Johto elite four first.
The boulder badge, the cascade badge, the thunder badge, the rainbow badge, the soul badge, the marsh badge, the volcano badge and the earth badge.
KANTO
It is located on Cinnabar Island.
Cearilian City (You have to wake snorlax up first, then you go find misty at the end of route 25)
i think its the rainbow badge from erika in celadon city
Johto 1: Falkner of Violet City (Zephyr Badge) Johto 2: Bugsy of Azalea Town (Hive Badge) Johto 3: Whitney of Goldenrod City (Plain Badge) Johto 4: Morty of Ecruteak City (Fog Badge) Johto 5: Chuck of Cianwood City (Storm Badge) Johto 6: Jasmine of Olivine City (Mineral Badge) Johto 7: Pryce of Mahogany Town (Glacier Badge) Johto 8: Clair of Blackthorn City (Rising Badge) Kanto 1: Lt. Surge of Vermillion City (Thunderbadge) Kanto 2: Sabrina of Saffron City (Marshbadge) Kanto 3: Erika of Celadon City (Rainbowbadge) Kanto 4: Misty of Cerulean City (Cascadebadge) Kanto 5: Janine of Fuchsia City (Soulbadge) Kanto 6: Brock of Pewter City (Boulderbadge) Kanto 7: Blaine of Seafoam Islands (Volcanobadge) Kanto 8: Blue of Viridian City (Earthbadge)
cinbar islnd
misty
The last gym badge is in viridian city for Kanto. For Johto it is in Blackthorn city.
go to kanto and beat lt surge
You beat the 6th gym leader.