Pokemon Heart Gold and Soul Silver are the respective reincarnations of what is presumed to be the best generation given to the Pokemon World, Pokemon Gold and Silver. Annouced May 8th, 2009 on Japan's official Pokémon website, Pokémon Heart Gold and Soul Silver will be released close to the ten year anniversary of the original counterparts.
Not much else is known about Pokemon Heart Gold and Soul Silver. Derived from Pokémon Sunday pictures, it is apparent that your starter Pokemon (Chikorita, Cydaquil or Totodile) will tail you like Pikachu in Pokemon Yellow from time to time, if not at all times.
Pokémon HeartGold & SoulSilver: Jagged-Ear Pichu Event:
If you transfer the Pikachu-Colored Shokotan Pichu from Pokémon Movie 12 to Pokémon HeartGold or SoulSilver, you can unlock a special in-game event. In order to activate the event, put the Pikachu-Colored Pichu in your party and travel to the Ilex Forest to encounter a Jagged-Ear Pichu. The Jagged-Ear Pichu will start a foot race and then decides to walk with you. It is not yet confirmed that the Pichu will join your party, but the videos from Oha Suta make it pretty evident that it will.
The Jagged-Ear Pichu featured on Oha Suta was a female at level 30. It knew the moves Helping Hand, Volt Tackle, Swagger and Pain Split. We'll update this page with more details as they come.
Pokémon HeartGold & SoulSilver: Arceus Event:
If you transfer the Arceus that was distributed at the movie theater during Pokémon Movie 12 (Arceus: To the Conquering os Spacetime) to Pokémon HeartGold or SoulSilver, you can witness the birth of a legendary Pokémon! In other words, you can receive a level one Giratina, Dialga or Palkia if you transfer the Eigakan Arceus to HeartGold or SoulSilver.
In order to activate the in-game event and receive one of the three legends, you must bring your Arceus to the "Shinto Ruins". When you arrive there, a man will approach you and ask: "Is this the Pokemon from Sinnoh called Arceus?!". He will then allow you to enter the shrine, and it is here that the player meets Cynthia. There is an exchange of words and then Arceus steps into the center of the design on the floor. This causes several Unown to appear in a swarm. An egg then appears and begins to crack. Inside the egg is one of the three legendary Pokémon.
More details will be added to this page as more information is released.
Pokémon HeartGold & Soul Silver: The Bag:
The Bag that the player is given in Pokémon HeartGold & SoulSilver is a much more sophisticated bag compared to any of the previous generations. The HeartGold & SoulSilver bag has made the items storage obsolete in that it is capable of storing infinite amounts of items. The main function of the Bag has also been moved to the touch screen portion of the DS.
Obtaining Kyogre, Groudon, and Rayquaza:
The Elemental Trio from Hoenn, Kyogre, Groudon and Rayquaza, will be obtainable in Pokémon HeartGold and SoulSilver. To obtain Kyogre and Groudon the player must first defeat the Elite Four. Once the player has done so they will be able to capture either Kyogre in HeartGold or Groudon in SoulSilver.
As for Rayquaza, it seems as though once the player has both Kyogre and Groudon on HeartGold or SoulSilver Rayquaza will then be obtainable.
Pokémon Heart Gold & Soul Silver: The New PokéDex:
With the release of Pokémon Heart Gold & Soul Silver the will be a new PokéDex introduced. This new PokéDex will produce a much cleaner and organized look for browsing Pokémon. The PokéDex comes in the standard red color and a light pink version, assumably to be for the female counter-part character.
The PokéWalker is a pedometer which will be bundled with Pokémon HeartGold and Pokémon SoulSilver. The PokéWalker allows you to transfer one (1) Pokémon from your game using infrared technology. While the Pokémon is on the device, it will gain experience and happiness.
When a Pokémon is uploaded to your PokéWalker, you will occasionally come across items and other Pokémon while you venture across various courses. In addition, the steps you take while walking with the pedometer are converted into "watts" which can be used to play minigames. Please note that the watts you obtain are based on a ratio of how many steps you take. Therefore your actual step count does not reflect the same watt number.
The PokéWalker: Courses:
After transferring a Pokémon to the PokéWalker, the Pokémon will "walk" through a specific course. There are two courses to select by default, but as you progress through the game, more courses can be unlocked. Courses can also be unlocked using special methods. For instance, sending an event Pokémon to your HeartGold or SoulSilver version may unlock a new course. Each course has specific characteristices that determine which Pokémon and items you may encounter. Below is a table with all the currently known courses and how you can unlock each one.
The PokéWalker: Minigames:
As mentioned above, you accumulate watts as you walk. These watts can be used to unlock various minigames.
In one minigame, you can use the PokéRadar to capture wild Pokémon. There are four patches of grass and there is a Pokémon in one of them. If you select the right patch and encounter the Pokémon, you will be able to battle it, capture it and send it back to your game.
In another minigame, you use the Item Finder to look for items and pick them up as you find them. However, there are only a limited number of chances to find the item in the grass. If you do manage to get one, you can send it back to your game as well.
Walking With Your Pokémon:
Up until now, with the exception of Pikachu in Pokmon Yellow version, trainers had to keep their Pokémon in Pokéballs and could only let them out during battles. This time around, you can let the lead Pokémon in your party out of its Pokéball and walk around with it! Not only can you walk with your starter Pokémon, but you can walk with any Pokémon, including legendary Pokémon!
In Pokémon HeartGold & SoulSilver, the player can interact with the Pokémon he/she is walking with. Similarly to Pokémon Yellow, the Pokémon will express emotions based on status or feelings when you face it and talk to it. For instance, the Pokémon may show a mad face if it has a low happiness level.
Pokémon and Items:
The Pokémon which the player is walking with also serves another purpose in that it has the ability to pick up items. The picture to the right shows a Wobbuffet that found an accessory. At this point, it is not known whether some Pokémon can pick up items that others can't.
All credits go to Project Pokemon