The Pokémon capture animation while on the items menu
The Park Ball glitch, also known as the Park Ball battle mode graphics corruption glitch is a glitch in Pokémon Gold, Silver and Crystal.
It is not a natural glitch, as another glitch such as arbitrary code execution or the bad clone glitch is required to obtain a Park Ball in the player's inventory, outside of the Bug-Catching Contest.
Using the Park Ball outside of the Bug-Catching Contest will activate the ball animation without closing the items menu. This causes the graphics to become glitched, and a glitch Pokémon sprite can momentarily be seen.
If the Pokémon breaks free, the colors may glitch out momentarily before returning to the main battle screen.