Altering Cave - Pokemon Fire Red and Leaf Green Guide - IGN

Found north of Sixth Island, this cave only have Zubats. However, if you have an E-reader connected to a gameboy advance using Japanese E-reader cards

Pokémon FireRed and LeafGreen/Cerulean Cave — StrategyWiki

Pokemon LeafGreen Version [Walkthroughs] - IGN

Pokémon FireRed & LeafGreen - Altering Cave

Medali Gym (Normal) - Pokemon Scarlet and Violet Guide - IGN

Pokemon LeafGreen Version [Walkthroughs] - IGN

Altering Cave - Bulbapedia, the community-driven Pokémon encyclopedia

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PK3/WC3: Unreleased Altering Cave Pokémon - Unreleased/Beta PKM

PK3/WC3: Unreleased Altering Cave Pokémon - Unreleased/Beta PKM

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PK3/WC3: Unreleased Altering Cave Pokémon - Unreleased/Beta PKM