In the game's code is evidence of an unused Event Pokémon. Event Pokémon are exclusive Pokémon throughout the franchise's history which usually have movesets or other unique properties that would not otherwise legitimately occur in normal gameplay.

A code string indicates that Diglett learns the move "Acid" at Lvl. 1, found at the end of Diglett's Generation 1 move pool, as this programming method was the manner in which the programmers ensured Event Pokémon transferred via the Game Pak to Stadium could function properly during gameplay.

To date, a Diglett with Acid being legitimately learned in it's moveset has never been released or distributed by an official Event by Nintendo nor Game Freak.