nevermind i found it
How to get to lost cave in leaf green??
It is in Five Island
lost cave
That item doesn't exist in leafgreen their is a sea incense and lax incense in the cave.
in the lost cave on island five
Its in Lost Cave in one of the Sevi Islands.
you find lost cave on leaf green on 5 island. after resort gorgeous.
You can find wild haunters in Pokemon tower and lost cave.
Sea incense is found in lost cave.
Once you have the silph scope you can go inside Pokemon tower and randomly on the floors where its foggy gastly can appear. Also you can find gastly inside lost cave on five island.
Go to five island. Surf north to Resort Gorgeous then surf east from there to find lost cave.
Random, but the more trainers you see, the closer you get to the lady.