With the release of Pokémon Crystal on the Virtual Console for 3DS, Celebi (shiny and non-shiny) can be transferred up using Pokemon Transporter,
due to the fact that VC Pokémon Crystal allows players to get the GS BALL legitimately (without hacking or glitching).
However, Pokémon Crystal was not released to the Korean 3DS's, neither in Korean (as Korean Pokémon Crystal didn't exist back in the day) nor in international languages (as in Korean 3DS never got it).
As such, the only Virtual Console games that do not have access to Celebi are the Korean versions of Generation II,
as the Korean Virtual Console titles cannot communicate with the Japanese nor International versions.
While it would be illegal, Pokémon Transporter allows the transfer of a Korean Celebi from Generation II.
This page contains a shiny and non-shiny Celebi modeled after the one caught in Ilex Forest of Pokémon Crystal.