From Bulbapedia, the community-driven Pokémon encyclopedia.
During the planning and development stages of Pokémon HeartGold and SoulSilver, CoroCoro magazine released some information about the upcoming game including game sprites and locations. Everything in the article was found in the real game with a few modifications and clean ups.
Before the game was released, there were pictures from CoroCoro Magazine that showed Silver's, Chikorita's, Pikachu's and Pikachu-colored Pichu's beta sprites. These were changed later on. There is also a beta back sprite of Ethan. His hair is slightly different and there is a symbol on his hat.
Beta screenshots also exist, one of the Slowpoke Well that instead shows a Team Rocket grunt standing where Proton is in the final version, as was the case in the original games, and another of the Mystri Stage in Sinjoh Ruins that shows the three circles being identical instead of three different colors in the final version.
Also, Cyndaquil's sprite in the intro is different from its front sprite in the main game. This may be something in the beta version that was forgotten to be edited in the intro.
Beta back sprite of Ethan
Beta battle screen, showing Ethan and Silver's aforementioned sprites
Chikorita's beta sprite (leaf coloring is darker)
Pikachu-colored Pichu's beta sprite
Beta version Mystri Stage, a platform in Sinjoh Ruins used for summoning one of the Sinnoh game mascots.
- The Photo Album was going to be a key item, but the feature was included in the PC instead.
- Data, including a sprite, exists for the Slowpoketail. It can be obtained through hacking but has no function.