To celebrate the upcoming Pokémon games, Pokémon Black Version and Pokémon White Version, which will be released in Norway and other European countries March 4th, Nintendo and Norwegian electronics and video game store chain Spaceworld give Pokémon fans all over the country an opportunity to catch the mysterious Pokémon Celebi in all Spaceworld stores between February 14th 2011 and March 4th 2011.

This is the only possible way to acquire this Pokémon, as it has never been available to catch in any video game.

By visiting a Spaceworld store in the time period February 14th - March 4th, and bringing along a Nintendo DS, Nintendo DSi or Nintendo DSiXL as well as one of the following five games, you will receive this exclusive Pokémon.

It can be transferred to the following games, which one must bring along with one's DS system:
Pokémon Soul Silver, Pokémon Heart Gold, Pokémon Diamond, Pokémon Pearl, Pokémon Platinum. By having Celebi transferred to a Pokémon Black or White game, one will also be given the opportunity to meet a completely new Pokémon; ZORUA!!

One will not be able to meet this Pokémon unless one has transferred Celebi to one's Pokémon game. It is assumed that Celebi will be available in other stores across Europe in the same time period, though nothing has been confirmed yet. NOTE: Celebi can not be transferred to other systems or other games.

Source: http://www.spaceworld.no/fang-den-mystiske-Pokemon-celebi-hos-spaceworld/