Making a secret base and decorating it in Pokémon Emerald/Ruby/Sapphire was so fun. Damn I really miss this. And I still have my saved file. : r/Gameboy
Pokemon Brilliant Diamond Shining Pearl: How to Get a Secret Base
Upper Mantle - The Pokemon Insurgence Wiki
Pokémon Ruby & Sapphire - Secret Base
Pokémon Omega Ruby & Alpha Sapphire - Super-Secret Bases