Lucario used Flash Cannon to break the rock in the front of the ship that Diamond was on to pieces before the ship was able to hit it. A small boat arrived next to the ship, revealing Lucario was the one who broke the rock, and its trainer introduced himself to Diamond and stated that he was picking him up to train on Iron Island. Riley sent Lucario to train Diamond, who used Tru, Lax and Don to face him. The latter three used Razor Leaf, Rollout and Iron Tail, but were hit from Lucario's Close Combat. Moreover, Lucario used Aura Sphere to inflict more damage to them, but Don and Lax went under Tru's tree to protect themselves. Tru then used Wood Hammer, to attempt to crush Lucario, but the three Pokémon got hit by Aura Sphere, which fell from the sky. Since the three Pokémon were exhausted, Riley stopped the battle, and announced he had won it. Lucario continued to accompany Riley, and the two were observing Diamond's training. At night, Lucario sensed something, but nothing happened.
Riley gave Diamond the task to retrieve the egg. Since Steelix was blocking Diamond's path, Riley and Lucario went with him to find another route. Suddenly, the two were attacked, and honey was splattered over their eyes, so they could not see. Two roughnecks appeared, whose Vespiquen performed the attack. Moreover, their Mothim used Air Slash around them, so Riley and Lucario could not sense their aura from this aura seal. However, after Diamond managed to hit their Vespiquen and Mothim could not keep up, Lucario and Riley regained their senses. Thus, Lucario used Flash Cannon, Aura Sphere, Close Combat and Bone Rush to defeat the two roughnecks. Lucario carried Riolu, who hatched from the egg. When Diamond saw a photo of Byron and Roark, he saw Riolu and Lucario, as family he needed to protect from Team Galactic.
Riley and Lucario encountered Sird atop the Spear Pillar. Riley remarked that the person that controlled the grunt was Sird, who appeared on the machine. To fight her, Riley had Lucario attack her Starmie with Close Combat and Aura Sphere. Sird, however, much to Riley and Lucario's surprise, retreated with her Starmie.
Later, Lucario appeared with Riley, and used Bonemerang on Palmer at the Battle Zone. Palmer caught the bone, and was pleasantly surprised to see them. The two helped Palmer and Argenta investigate the communications systems. In fact, Riley sensed a force, much like the one at Spear Pillar, coming from outside the Battle Frontier. Riley and Lucario, along with Darach and Thorton, awaited Palmer and Platinum. The two came to help protect the Sinnoh Battle Frontier.
Riley had Lucario and Riolu use their aura to clear the electromagnetic field to follow the spy drone, even as they sailed on the sea. They went to the Sinnoh mainland, and disboarded at the Sendoff Spring.
- ^ D&P041: Grumpy Gliscor
- ^ D&P042: Lucky Lucario I
- ^ D&P043: Lucky Lucario II
- ^ D&P044: Vexing Vespiquen & Unmanageable Mothim I
- ^ D&P045: Vexing Vespiquen & Unmanageable Mothim II
- ^ D&P077: Double Trouble with Dialga and Palkia IV
- ^ a b PT002: Deprogramming Porygon-Z
- ^ PT011: Uprooting Seedot
- ^ PT013: Dealing with Dragonite
- ^ PT016: The Final Dimensional Duel II
- ^ PT017: The Final Dimensional Duel III
- ^ PT019: The Final Dimensional Duel V