Ash arrives at the Canalave Gym, ready for a battle, but there's yet another snag: Gym Leader Byron's son is in town, and that son is Roark, the Oreburgh Gym Leader! The two of them have a lot to work out; not only do they argue over who loves fossils the most, Roark is still angry at Byron, the former Oreburgh Gym Leader, for abandoning the family and running off to Canalave City. To clear the air, Byron and his Bastiodon will battle Roark and his Rampardos in an exhibition match, and Ash's battle will just have to wait!

Bastiodon's strength is its defensive capability, and its Iron Defense easily absorbs Rampardos's Zen Headbutt attacks. Even though Rampardos keeps up a tough offense, it just can't crack Bastiodon's defense, and it's starting to get tired. Then the Gym alarm sounds—Team Rocket has dug into Byron's exhibition room and escaped with all of his fossils, which means the battle is over! Ash and his friends follow as Byron and Roark jump into the tunnel dug by Team Rocket, catching up with the thieves outside the Gym. As much as Byron admires Team Rocket's digging prowess, he and Roark want those fossils back!

Bastiodon and Rampardos take on Team Rocket's Mecha Man robot, which is holding all the fossil loot. By working together, they're able to smash holes in the back of the robot, but they can't get any closer to finish it off. That's when Pikachu comes to the rescue, blasting the damaged mecha with electricity and sending Team Rocket on their way. As Byron and Roark retrieve the stolen fossils, Roark finds the Sunkern fossil he gave his dad long ago. It seems Byron does care about him after all—in fact, Byron left the family in Oreburgh so that Roark could become his own Gym Leader, not just Byron's apprentice. Now father and son are finally reconciled, and Ash can finally battle Byron at last!