Ruin maniac's cave
From Bulbapedia, the community-driven Pokémon encyclopedia.
on route 214,Sinnoh you will notice a cave on that platform inside that cave is the ruin maniac's cave. It starts out a small room in a mountain but after a unknown amount of time (possibly post nationaldex) there are only two Pokémon:Hippopotas and Geodude. there is also a CPU character in there that character is the ruin maniac. He appears to be a regular Pokémon collector instead of a ruin maniac. before the expansion he asks if you can race him. This is a possibility that if you capture a certain amount of unown then it will extended.
