In Pokémon Crystal, lies an event encounter whereby users get to challenge, and potentially capture, the Mythical Celebi.
In the Japanese versions of Pokemon Crystal, this encounter required the usage of the Mobile Communication Device.
As of 26th January 2018 12AM (Japan time), Pokémon Crystal has been released to the Virtual Console of the Nintendo 3DS, with the only requirement for obtaining it being defeating the Elite Four. (Any instance would unlock the flag. Any other step, such as