A few years later in the Sinnoh region, Garchomp and Spiritomb were seen next to Cynthia as she suspected and saw Diamond's Tru, Pearl's Chimler and Platinum's Piplup evolve. As she spoke to Platinum and her newly-evolved Prinplup, Garchomp was next to her. She also appeared outside the mysterious building and when she left Eterna City.
Garchomp reappeared with Cynthia in Mr. Backlot's mansion, to the shock of Diamond and Pearl. Later on, as a quick way to get to Route 210, she decided that Dimaond, Pearl and Platinum should ride on Garchomp as she rode her bike, as she was going there to clear the Psyduck that were blocking the path.
While inside and outside of Cafe Cabin, Garchomp was with the group. As she was going to return one of the Psyduck to a trainer in Amity Square and going back to Mr. Backlot, Cynthia left Garchomp in the care of her grandma. While arriving in Celestic Town, Garchomp sensed something. Diamond thought it was annoyed, but Cynthia's grandma corrected him, saying that she's preparing for battle. As it looked at the mines of a Probopass, it sensed something from the roof of a building. Suddenly, a Magnezone from the roof used Charge Beam at Garchomp, causing it and Diamond's Munchlax to fall back. Then, grandma had Garchomp use Dragon Rush on Cyrus' Probopass and Magnezone, once he introduced himself, but they dodged the attack. It used Hyper Beam on his Probopass, causing it to be knocked out. Pearl alerted Garchomp that Magnezone was about to launch Mirror Shot and was able to dodge it. Garchomp launched a counterattack, but Magnezone was able to dodge it. The attack hit the cave that Cyrus wanted to get into as Cyrus revealed that the Mirror Shot lowered Garchomp's accuracy. While Cyrus was inside the cave, Garchomp and the rest of the group spied to on him to hear what he was saying. Pearl suggested they a getaway from the situation, in which Garchomp was used, but Diamond and his Pokémon were left behind. After the commotion with Cyrus, grandma and Garchomp said goodbye to Diamond, Pearl and Platinum as they were with Fantina on her Drifblim.
When arriving back in Celestic Town and talking to her grandma about a scroll, Garchomp was with her.
Towards the end of her battle against Cyrus, she sent out Garchomp and that she wanted revenge. Garchomp bit into Cyrus' Gyarados. Seeing how angry she was, Cynthia decied to use the ultimate move, Draco Meteor, to the shock of Cyrus and Gyarados. He noticed that Gyarados still had the energy to battle but Garchomp didn't. She decided to go to Mt. Coronet on Garchomp as Cyrus went off there and after realising what he was meant in what he was saying to her.
Cynthia and Garchomp entered the room where Uxie, Mesprit and Azelf, where discovered Diamond, Pearl and Platinum on the floor instead. She had her carry them while on their way to Mt. Coronet, while she rode her bike.
While at the foot of Mt. Coronet, Garchomp was seen with the group. As a piece from Mt. Coronet was falling towards them, she protected Cynthia and Platinum. At Spear Pillar, Garchomp charged with Cynthia, Diamond, Pearl and Platinum, Dialga and Palkia blew them back. When she landed, Platinum wanted to help Diamond and Pearl, but with Cynthia and Platinum, they saw the Gym Leaders, defeated. She along with Cynthia and Platinum, were looking for Cyrus, who suddenly disappeared. As Platinum was reading a scroll, Garchomp protected her from flying debris, caused by Dialga and Palkia's battle. When they heard Cyrus' voice, Garchomp also looked for him. When the ditortion in time and space was happening, along with everyone in the group, Garchomp was shocked.
A couple of weeks later in Veilstone City after the chaotic event at Spear Pillar, Garchomp was seen with Cynthia as she was speaking to her grandma.
|Dragon Rush||Problematic Probopass and Mad Magnezone I|
|Hyper Beam||Problematic Probopass and Mad Magnezone I|
|Draco Meteor||Shunning Spiritomb|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.
- ^ D&P010: Ring Around the Roserade II, Garchomp does not have a grooved fin
- ^ HGSS019: All About Arceus XI
- ^ D&P010: Ring Around the Roserade II
- ^ D&P030: Suffering Psyduck!
- ^ D&P031: Problematic Probopass & Mad Magnezone I
- ^ D&P032: Problematic Probopass & Mad Magnezone II
- ^ D&P033: Problematic Probopass & Mad Magnezone III
- ^ D&P047: Maddening Magby
- ^ D&P069: Halting Honchkrow
- ^ D&P072: Shunning Spiritomb
- ^ D&P074: Double Trouble with Dialga and Palkia I
- ^ D&P075: Double Trouble with Dialga and Palkia II
- ^ D&P076: Double Trouble with Dialga and Palkia III
- ^ D&P077: Double Trouble with Dialga and Palkia IV
- ^ D&P078: Double Trouble with Dialga and Palkia V
- ^ PL015: The Final Dimension Duel I
- ^ PL024: The Final Dimension Duel X
- ^ PL025: The Final Dimension Duel XI