It has to do with kyurem the legendary ice/dragon type
Because Kyurem covered half of it in ice. For what reason it is not known as it happened during the two years that separate Black/White from Black/White 2. It might be revealed later but as of now nobody could tell you except gamefreak.
covered half of it in ice. For what reason it is not known as it happened during the two years that separate Black/White from Black/White 2. It might be revealed later but as of now nobody could tell you except gamefreak.