Pokémon Ruby Version, Sapphire Version, and Emerald Version - Terrain
For the purposes of Camouflage, Nature Power, and Secret Power, Phenac Stadium is treated as "underwater", Pyrite Colosseum is treated as "rocky ground", Deep Colosseum, Realgam Colosseum, the Under Colosseum, and Mt. Battle areas 1 through 30 and 61 through 99, are treated as "elsewhere", Orre Colosseum is treated as "sand", and Mt. Battle areas 100 and 31 through 60 are treated as "rocky ground."
Fishing is treated as "moving water" or "still water", depending on where the Pokémon was fished.