The game takes place in Sinnoh, which is based on the island of Hokkaidō in Japan. The new criminals are Team Galactic. The game features an updated day/night system, as well as Pokémon Contests, the Battle Tower, a Pokétch device, and Wi-Fi abilities.
You can battle and trade using the Wi-Fi connection. Diamond and Pearl is also be able to connect to the Wii game Pokémon Battle Revolution, where you are able to trade Pokémon from Diamond and Pearl to Battle Revolution and vice versa.
Also, you are able to transfer Pokémon from the previous Game Boy Advance games onto Diamond and Pearl after reaching a certain point in the game. You must have the GBA game in the GBA slot of the original Nintendo DS or DS Lite to do this.
The games chronicle the adventures of a new Pokémon trainer who strives to become the Pokémon League Champion by collecting and training Pokémon. Like most games in the series, Diamond and Pearl feature eight Pokémon Gyms led by Gym Leaders, professional trainers whose expertise lies in a particular Pokémon type. Gym Leaders serve as bosses and reward skilled trainers with Gym Badges, key to the advancement of the plot. As with all core games, the protagonist must also thwart the schemes of a crime syndicate, in this case, Team Galactic, who plan to use Pokémon to create a new universe just for themselves, while destroying the current one.
As with all other Pokémon role-playing games, Diamond and Pearl begin in the protagonist's hometown. After viewing a television report about a media-conducted search for a red Gyarados, which was spotted at a faraway lake, the protagonist and their best friend, Barry by default, travel together to check the local lake for a Pokémon like it. They spot Professor Rowan, a Pokémon evolution researcher, and his assistant, the playable character not selected in the game: Lucas (boy) or Dawn (girl). After a short discussion, the professor and his assistant leave the lake, leaving a briefcase behind. When they are attacked by a wild Starly each, the protagonist and their rival decide to examine the briefcase. They are then given a choice of one of three Pokémon found within—the Grass-type Turtwig, the Fire-type Chimchar, or the Water-type Piplup—and proceed to battle the attacking Pokémon. After defeating the Starly, Lucas or Dawn retrieves and returns the briefcase to the professor. Noticing that a bond has been forged between the young protagonist and his or her chosen Pokémon, Rowan offers it to them, asking that they embark on a journey and fill their Pokédex.
The protagonist encounters the antagonistic group, Team Galactic, early in the game, when he or she must save Professor Rowan from some of their thugs; however, their motives are unclear until later. The player encounters Team Galactic again when they take over a wind farm and when they set up a base in Eterna City, before eventually taking over Sinnoh's three lakes in an attempt to capture the Mirage Pokémon Uxie, Azelf, and Mesprit. Shortly after the player earns their seventh Gym Badge, Team Galactic captures the Mirage Pokémon and imprisons them inside the science laboratory of the Team Galactic Headquarters Building, where its members extract crystals from the Pokémon to create the Red Chain, an object that can control the legendary Pokémon Palkia in Pearl, or Dialga in Diamond. After releasing the trio, the protagonist is able to access Spear Pillar, an ancient ruin atop Mt. Coronet, where the leader of Team Galactic summons Dialga or Palkia. The legendary Pokémon's powers begin to overwhelm Sinnoh, causing the newly free Uxie, Azelf, and Mesprit to attempt to stop it. The player then battles Palkia or Dialga, and after defeating or capturing the Pokémon, Sinnoh returns to normal. Afterwards, the player continues their journey, eventually making it to the Sinnoh region Pokémon League's Elite Four. After defeating all four members, they then battle the Sinnoh League Champion, a woman named Cynthia, who had appeared before in the game. After the protagonist defeats Cynthia, they become the new Sinnoh League Champion, finishing the main story. In the post-game, there is a new island to explore that contains Pokémon not seen in the main game, and has some new stores and a tournament center. The protagonist's old friend, who challenged them to battles multiple times before, will also be waiting for them here and will challenge them to one more battle.
As in every Pokémon game (with the exception of Yellow), you must choose one of three pre-selected Pokémon to be with you in your party. The three new Pokémon this time around are Turtwig, Chimchar, and Piplup. The starters then evolve respectively into Grotle, Monferno, and Prinplup. The final evolutions are Torterra, Infernape, and Empoleon.
Once it was released in Japan on September 28, 2006, it was the fastest selling Nintendo DS video game to date, and has since been the best selling Pokémon game in Japan, selling a whopping 5 million copies in a few months.
Additionally, in preparation for the game to arrive, sales on previous Pokémon Game Boy Advance games has boosted.
The reception was very good. From IGN.com, who awarded it a 8.5 out of 10 to GameSpot.com who gave it another 8.5 out of 10, it was greatly liked. When reviewers fell in love, the public followed. All users adored the game. Many of this great reception is for the touch screen interactions, better and smarter A.I. in battles, improved graphics and a great Lasting Appeal, and also for it's length of 40 hours.
Pokémon Platinum is an enhanced version of Pokémon Diamond and Pokémon Pearl. It has a few new upgrades and the Battle Frontier has returned. It has the Pokémon Giratina as its mascot. It also had a few minor changes like meeting Cyrus in the beginning of the game and newer forms for Rotom, Shaymin, and Giratina.
Pokémon Brilliant Diamond and Shining Pearl are enhanced remakes of the games and were released for the Nintendo Switch on November 19, 2021, 15 years after the original games. Unlike previous games of the series, the game was developed by ILCA. The game received mixed reception due to poor overworld graphics, same battles as in the originals, and lack of other decent features such as Mega Evolutions.
Pokémon Legends: Arceus is an action role-playing game which serves as a prequel to Diamond and Pearl and is set in an older version of the Sinnoh region, the Hisui region. It is scheduled for release for the Nintendo Switch on January 28, 2022.
- The item Azure Flute is programmed into the games but was never released via Nintendo event. This would have led to a secret stairway in the Hall of Origin, and Arceus could have been caught there.