The GS Ball (Japanese: 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.
An NPC in Pokémon Ultra Sun and Ultra Moon mentions the GS Ball, claiming that it stands for greatest smith's ball (Japanese: ガンテツすごいボール Gantetsu's Superb Ball) or Gold-Silver Ball (Japanese: ゴールドシルバーボール Gold-Silver Ball).
In the games
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 and returned, Ilex Forest becomes restless, and the player must place it on the Ilex Forest shrine, which will summon a level 30 wild Celebi.
In the original Japanese release of Pokémon Crystal, players could obtain a GS Ball as an event item from the Trade Corner attendant through the Mobile System GB and the Pokémon News Machine at the Pokémon Communication Center in Goldenrod City.
For the original 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 Virtual Console releases, the GS Ball no longer requires an event distribution as in the original games. It can be obtained after entering the Hall of Fame upon exiting the Pokémon Communication Center in the Japanese version or the Goldenrod Pokémon Center in the Western localizations.
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 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 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 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
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 the ball and set Celebi free.
In other languages
Greatest smith's ball