Diamond (Adventures)/History/Platinum

It is later revealed that the notebook that Kit had stolen from Charon was a book with information on Legendary Pokémon. Joined by the Sinnoh Pokémon Association Chairman and Dr. Footstep, Diamond and Pearl use the notebook that was deciphered by the Sinnoh Elite Four and search for the Legendary and Rare Pokémon of Sinnoh.

Their first stop is to return to the Old Chateau where they find the Pokémon that had attacked them in their last visit,. The two are attacked by Rotom and its many different forms. Eventually, Diamond manages to bond with Rotom and befriends it; Rotom then joins their group.

Soon after, Diamond and Pearl hear a large noise and runs to the location where it came from. Upon arriving, they find a giant dragon Pokémon called going on a rampage and destroying Eterna City. Immediately, Reg erupts from its Poké Ball to battle Giratina. Soon after, Charon appears and reveals that intends to kill Diamond and Pearl in his plan to capture the Legendary and Rare Pokémon of Sinnoh.

Diamond and Reg face off Charon's while Pearl goes off to battle Giratina alone. With Reg's powerful, they manage to nearly defeat Heatran. When Charon forces Giratina to use, Diamond pushes Pearl out of the way of the attack, but gets hit by it in the process and is knocked unconscious. Much to Pearl's distress, he tries to wake Diamond up, but to no avail.

Seeing that its Trainer has died, Reg appears to leave, but soon returns with Rotom's appliances so that it can attack Charon in its rage. Together, Reg and Rotom force Charon and Giratina to retreat back into the Distortion World. Soon after, the Sinnoh Chairman and Dr. Footstep return to the scene after hearing all of the commotion. As soon as they return, Diamond's body suddenly begins to distort and disappears.

Later, Diamond awakens in another world, confused at his current surroundings. He quickly figures out that he is in the Distortion World, having touched it three times prior. There, he encounters Cyrus, and asks him if he knows how to beat Giratina.

Cyrus takes him to an area where Giratina had trapped Dialga and Palkia in a mineral after it dragged them into the Distortion World. Together, they free Dialga and Palkia from their prison. They ride the two dragons back to where Pearl and Platinum's groups were and reunites with Paka and Uji. After Diamond and Pearl return Paka and Uji's sunglasses, the Advanced level Grunt returns the stolen Pokédexes back to their proper owners.

As the battle between the Legendary Pokémon continues getting more and more chaotic, everyone begins to gather together. When Charon decides to escape, Diamond, Pearl, and Platinum each take a different Legendary Pokémon to fly and chase after him before he can trap everyone inside the Distortion World. They fly and eventually make it outside to Sunyshore City, where Charon is finished off by a surprise attack from Cynthia.

Charon tries to escape like he did at the Spear Pillar, only to be cornered by Diamond, Pearl, and Platinum. Although defeated, Charon refuses to give up, and uses his machine to try and make Diamond, Pearl, and Platinum's Pokémon attack each other. The machine is quickly destroyed by a toy of Proteam Omega, which is revealed to be possessed by Rotom.

With Charon defeated, everyone who was left behind in the Distortion World emerges from it safe and unharmed. Cyrus disbands Team Galactic, but thanks the three before leaving with Mars, Saturn, and Jupiter. Giratina tries to attack one last time, but is stopped by Volkner and Flint and is driven back into the Distortion World by Dialga and Palkia, this time without any desire for revenge.

Charon is arrested by Looker, who gives Diamond a Pokémon Egg given to him from the Fiore Region before leaving to his next mission in Unova. Having emerged from everything victorious, the three give each other a fist bump. Later, Platinum watches as the sole audience member as Diamond and Pearl gives her a comedy routine, which she hadn't seen in a while.

Sometime later, at the Solaceon Day-Care Center, Diamond plays with, a Pokémon that hatched from an Egg. Pearl berates him for playing with it when they are supposed to be training it, which Diamond responds by having the Pokémon use. The owners of the Day-Care recall of a that hatched a Pokémon with a similar personality to his in the Johto region.