The Legend
The GS Ball has appeared in all three cannons of the Pokemon franchise, the game series, the anime, and the comic. In the anime series, it was the subject of much discussion among the main characters and was intended to have a large impact on the series before it was set aside and never mentioned again. In the comic series, its genesis was revealed: The main antagonist forged the GS Ball from the feathers of two of the most powerful legendary Pokemon, Lugia and Ho-oh. The game confirmed this origin.
Acquisition
In the Japanese version of "Pokemon Crystal," players could connect their Gameboy Color to their cell phones, which would allow them to trade Pokemon with other players. This was done at the Pokemon Communication Center, at which players could acquire the GS Ball. This is no longer active, and can now only be obtained through an Action Replay cheating device.
Use
The GS Ball's purpose is to be taken to the Ilex Forest shrine, where the players are prompted to use it. Upon using it at the shrine, the GS Ball opens, revealing its contents.
What's Inside
When the GS Ball opens, a Celebi emerges and attacks the player character. Celebi is one of the rarest and hardest to obtain Pokemon in the entire franchise. Only Mew and Shaymin are as rare and valuable. If players are able to weaken Celebi, they can capture it with a Pokeball as they would any Pokemon. In the anime, "Pokemon: Johto," however, the ball is never opened due to the fact that Celebi became the main character of the fourth Pokemon movie, making its appearance in the anime series redundant.