You have to defeat Erika.
You beat the 4th Gym leader
In Celadon city.Celadon City, Leader: Erika. Specialty: Grass. Prize: Rainbow badge.
the boulder badge from brock
Fuschia city.
In Vermilion city.
fuschia.
fap
The Rainbow Badge
Head to Cinnibar Island for your next badge.
vermillon city
Those items aren't in LeafGreen.
It's erika the grass type user. the badge is the rainbow badge
Vermilion city.