How do you find the gym leader of olivine gym?

The gym leader of the Olivine Gym in Pokémon Gold, Silver, and Crystal is Jasmine. To find her, follow these steps:

1. Enter Olivine City from the west.

2. Walk all the way to the east side of the city.

3. Enter the building on the right side of the street.

4. Jasmine is inside, just to the right.

Note that you must defeat Team Rocket at Goldenrod Radio Tower before she will battle you.