GS Ball

The GS Ball (Japanese: ＧＳボール GS Ball) is a Key Item exclusive to Pokémon Crystal. It is a special and mysterious Poké Ball whose 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).