From Bulbapedia, the community-driven Pokémon encyclopedia.
| Hurrah for Rapidash/VS. Rapidash
Hurrah for Rapidash/VS. Rapidash (Japanese: VSギャロップ VS. Gallop) is the 377th round of the Diamond & Pearl chapter in the Pokémon Adventures manga.
The round starts with Professor Rowan and Platinum's father rejecting Platinum's decision, thinking it is too dangerous. However, Platinum doesn't listen and calls out her Ponyta. Inspired by her determination, it evolves into Rapidash. She explains that she heard about Team Galactic's plan the previous night. After a conversation with Byron, he sends out Bronzong to prove Platinum's ability. Byron states that he agrees with Platinum and he says she reminds him about his son. He even tells about how one Trainer from far away got all the Gym Badges of her region in 80 days, and that with six Badges in 25 days already, Platinum is well on course to beat that Trainer's record. Her father finally allows her to go on her journey and permits Diamond and Pearl to escort her. Professor Rowan upgrades all of their Pokédexes and officially entrusts the Pokédex to Diamond and Pearl.
Pearl starts to panic again as he thinks about Team Galactic's plan, since he knows that they can't visit all three lakes together before they are all blown up at once. When Pearl sees the Ribbon that Empoleon kept, it reminds him of how he, Diamond and Platinum co-operated during Platinum's preparation for the Contest, and he realizes they have to work together again, in a different way. Pearl decides that the trio should split up and investigate each lake separately. Diamond and Platinum agree. Eventually, it is also agreed that Platinum should travel to Lake Acuity, Pearl to Lake Valor and Diamond to Lake Verity.
Pearl and Platinum immediately set off to their destinations. Diamond, however, is stopped by Byron, who takes Diamond to the harbor in Canalave, where the S.S. Sinnoh is docked. Byron has observed that out of the trio, Diamond is the least potent in battling, and therefore instructs Diamond to board the S.S. Sinnoh next morning to get to Iron Island, where a man called Riley will give him special training. Byron is also impressed by how easily Diamond was able to bond with his Shieldon no matter how hard Byron had tried to do the same, and allows Diamond to keep the Shieldon. Byron also gives Diamond a letter to pass to the captain who would be sailing the liner.
The next morning, Diamond has embarked on the S.S. Sinnoh with his team of Pokémon, including the new member, Shieldon, which he nicknamed "Don". At the same time, Pearl is leaving a lodge near Floaroma Town and Platinum is departing from a hotel near Celestic Town, both heading closer to their destinations. Diamond, Pearl and Platinum reminisce about how the "morning sound" of the Pokédex would wake them up each morning, with Pearl being the first to get ready, followed by Platinum, and then Diamond. The sound is evidently absent on the morning of their new, separate journeys. All three of them shed tears on their respective Pokédexes, knowing that they would be on their own, starting from that day.