Pokémon Crystal beta

introduced many features that have since become staples of the core series games, such as the option to pick a female player character undefined, animated sprites and  facilities with special rules. Likewise, some aspects of the game's initial design did not make it to the final release. However, it has fewer known pre-release elements compared to its companion games,, likely because it is heavily based upon them.

Pokémon Communication Center
A picture of the game's development later released by Game Freak revealed an earlier design for the Pokémon Communication Center. Fundamentally, the differences from the final design include an upper floor on the top-left of the map and two machine areas in the main floor instead of just one, one of which was replaced with a Trade Corner for use with the Pokémon Mobile System GB in the final release.

Female character
Although was introduced in, a development picture reveals that another girl was in the works. The girl had black hair in pigtails. She may have also been an attempt to include the female Trainer that was seen in artwork released during the development period of.

Music
An unused song is present in the game's code. However, the circumstances it would have been used for are unknown. Interestingly, the same song exists within and was actually used in the Japanese version.

Super Game Boy features
Despite being incompatible with the original Game Boy, Game Boy Pocket, Game Boy Light, the Super Game Boy and the Super Game Boy 2, there is an unused Super Game Boy border programmed into the game, which can be activated by setting a flag in the game's  to enable the Super Game Boy features. Cheating devices such as the can also be used to achieve the same effect, albeit only temporarily. The border is a leftover from the Japanese version of Pokémon Gold, since the design is the same and the text reads Pocket Monsters Gold Version, rather than Pokémon Gold Version as it does in the English version of Pokémon Gold. This could also suggest that Game Freak used Pokémon Gold as the basis for the development of Pokémon Crystal.

When the undefined attempts to play the game on a model of the Game Boy prior to the Game Boy Color, the "This Game Pak is designed only for use on the Game Boy Color." is output by the game, with the word Crystal spelled out using. There is an unused color palette associated with this message, using an orange tint, which appears when triggering the unused Super Game Boy border; this tint also appears if one force-boots Pokémon Crystal on a Super Game Boy.