From Bulbapedia, the community-driven Pokémon encyclopedia.
The GS Ball (Japanese, Crystal: ジーエスボール GS Ball, anime: ＧＳボール GS Ball) is a special and mysterious Poké Ball. Its design appears to be a reference to Pokémon Gold and Silver, the first core series games of Generation II, as the ball has the letters "GS" inscribed upon it and is colored both gold and silver.
In the games
In the Japanese version of Pokémon Crystal, players could use the Pokémon Mobile System GB and the Pokémon News Machine at the Pokémon Communication Center in Goldenrod City to obtain a GS Ball as an event item from the Pokémon Communication Center's Trade Corner attendant. After obtaining the GS Ball, the player needs to take it to Kurt, who will analyze it for a day. After it has been analyzed, the player must place it on the Ilex Forest Shrine during a period when Ilex Forest is suddenly restless, which will cause a level 30 wild Celebi to be summoned.
For Western localizations, the distribution event was adapted to the Goldenrod Pokémon Center but was never used. It is possible to use a modified version of the Celebi Egg glitch to spawn the GS Ball as a held item.
In the Korean versions of Pokémon Gold and Silver, the dummy item Teru-sama with ID 0x73 is labeled "GS Ball" (Korean: GS볼 GS Ball). This item ID is the same one used by the GS Ball in Crystal and Pokémon Stadium 2, and is called Teru-sama in Japanese and Western Gold and Silver.
| The mysterious Ball.
Receiving the GS Ball (Japanese version)
A "GS Ball" is one of three dummy items in Korean Gold and Silver
In the anime
In the anime, Professor Ivy was the first character to possess the GS Ball. She called upon the help of Professor Oak to study it, but couldn't figure out how to open it. Ivy tried to open it with hacksaws, hammers, crowbars, power drills and lasers, but to no avail. At one point, Ash tried simply calling a Pokémon to be released, but this did not work. The ball also couldn't be transmitted via PC.
In Pallet Party Panic, Professor Oak tasked Ash with retrieving the GS Ball from Professor Ivy's laboratory, located on Valencia Island in the Orange Archipelago, and bringing it back to Oak for him to study.
Ash obtained it two episodes later, in Poké Ball Peril, and updated Oak on his progress. He put off completing the errand in the next episode so he could compete in the Orange League, a move which Oak approved.
In Fit To Be Tide, Misty scolds her Psyduck for bouncing it up and down on its head.
In A Way Off Day Off, Ash compared it to a standard Poké Ball while everyone else was sleeping.
After a brief mention by Misty in The Underground Round Up, Ash finally gave Oak the GS Ball after returning to Pallet Town in A Tent Situation, but Oak put it away to examine later. The GS Ball was then last sucked in by Team Rocket's Super Sucker. When the trio's balloon was torn, the GS Ball was rescued with all the other Poké Balls.
In The Rivalry Revival, Oak's studies on the ball proved to be extremely difficult, with Tracey even admitting that no new information was gathered. Oak gave it back to Ash, asking him to deliver the GS Ball to Kurt of Azalea Town in Johto, a Poké Ball researcher and manufacturer.
In Once in a Blue Moon, Ash took the Ball out to polish it when it is stolen by a Quagsire. Ash, Misty, and Brock chased after the Quagsire before getting the Ball back by the end of the episode.
In A Shadow of a Drought, the trio arrived in Azalea Town, and Misty reminded Ash about the errand. The delivery was made in Going Apricorn!, and Ash broke the news to Oak in A Farfetch'd Tale. Its last appearance was in a flashback in Hour of the Houndour.
In an interview with Masamitsu Hidaka in 2008, it was explained that the GS Ball was originally going to contain a Celebi that was to be the star of a large arc of the Johto saga. However, it was decided that Celebi would be the star of the fourth movie, so the story arc was viewed as redundant and shelved. The ball was left with Kurt with the hopes that viewers would eventually forget about it.
For every episode of the anime's fourth season, Pokémon: Johto League Champions, three GS Balls are seen alongside the title card and the name of the episode. Each Ball is situated on a corner of the title card; there are two GS Balls on the two bottom corners and one on the top right corner.
In the manga
The GS Ball in Pokémon Adventures
In the Pokémon Adventures manga
The GS Ball was created by the Masked Man in the Gold, Silver & Crystal chapter using a net made from the feathers of Lugia and Ho-Oh to capture Celebi. Only the feathers of the two Legendary Pokémon could contain Celebi, and prevent their holder from suffering the ill effects of time travel. Gold was able to use Pibu to destroy it and set Celebi free.