How do you get your fourth badge in yellow?

Answer 1

the Gym is in Celadon City (the place with the bike route to Fuchsia City that has the 5th city and the Pokemon sarfari, and Celadon City has a under ground path to Lavendar town that has the Pokemon tower)

Answer 2

After you beat Lt. Surge, you have to go back to Cerulean City. Head east to Route 9 and enter the Rock Tunnel. It is important to have beaten Surge because it is extremely dark in it. Use flash if you want to, and head through. When you exit, head down, and you'll find Lavender Town. There isn't a gym here, so your best bet would be to head west to Route 8. You'll eventually stumble upon the Underground Tunnel that leads to Celadon City. The fourth gym is there. At the south end of the city, there will be a small tree. Use Cut (and trust me, you'll use Cut to get through the gym), and head left. You'll see the gym. Use Cut to get to the Gym Leader. Have fun battling Erika, our Grass-specialist!

Answer 3

I Tried Really Hard To find The Way But i Think Its not iN thE Game =(

Answer 4

At lavaridge town