Pokémon Yellow beta

Pokémon Yellow is a special edition of the Generation I games. It introduced the happiness system, which has since become a staple of the main series and other features, such as walking Pokémon (exclusive to itself and HeartGold and SoulSilver) and a Pikachu's Beach minigame. Few aspects of the game's initial design did not make it to the final release, either due to time constraints or due to its heavy reliance and basis on Red, Green, and Blue.

Battling with no Pokémon

Data exists for a battle situation when the Trainer has no Pokémon. In this case, selecting any option other than Run shows the message "Hurry, get away!" This may have been a prototype for the initial battle with the wild Pikachu at the start of the game (as the player has no Pokémon at that point) or against a wild Spearow with Pikachu unable to battle, leading to further reference to the anime.

Unused music

An unused track has been encountered in the game's programming. It is not known where it would be played but it is possible that it relates to the aforementioned no Pokémon battle system. However, it is not stored in either the battle, overworld or cave soundfont. It is located in the minigame and "special trainer" (Jessie and James) soundfont, where the Pikachu's Beach music is stored, which is partly why this track only exists in Pokémon Yellow. A sample from it can be listened to here.

Debug menu

A debug menu has been found hidden in the coding. It seems to be located within the Game Freak logo introductory screen and is only activated when hacking the game to load an invalid soundfont. Upon activation, the "obtained item" sound will play, despite only being audible if the original soundfont is put back quickly. The leftover text is illegible and the only option available is to exit the menu.