Pokémon FireRed and LeafGreen/Berry Forest

Berry Forest
Berry Forest is similar to Viridian Forest in that it's a natural maze. Bring a Pokemon that knows cut to skip the tall grass. However, a Pokemon that knows surf is required to get through Berry Forest and finally find Lostelle.

Devoid of trainers, Berry Forest doesn't have much for you to do.

Lostelle
Lostelle is the pink haired girl at the end of the forest. When you find her, she says that she's been locked down by a "scary" Pokemon. The Pokemon is a level 30 Hypno. Capture or defeat it to finally rescue Lostelle.

As a reward, you'll get an Iapapa berry and will warp to the Game Corner on Two Island.