Ancient Family Matters! (Japanese: ラムパルドＶＳトリデプス！！Rampald VS Torideps!!) is the 107th episode of the Diamond & Pearl series, and the 573rd episode of the Pokémon anime. It first aired in Japan on December 18, 2008 and in the United States on May 23, 2009.
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!
Byron, the Gym Leader of Canalave City, has finally returned from his training on Iron Island. Ash and his friends come to the Gym in order for Ash to have his Gym Battle with Byron. However, they are once again met by the Gym's referee who informs Ash that Byron cannot accept a challenge as he is currently arguing with his son. Upon entering the Gym Ash and his friends find Byron's son is none other than Roark, the Gym Leader of Oreburgh City. He greets Ash and friends, but then gets back to fighting with his father over who loves Fossils more. In an attempt to prove his love of Fossils Byron shows Roark, Ash, Brock and Dawn his collection of Fossils, including his special Anorith Fossil which is three times the size of a normal Anorith. Byron and Roark then begin to fight over who has the better revived Fossil Pokémon, Byron's Bastiodon or Roark's Rampardos. Ash suggests they battle to see whose Fossil Pokémon is better.
Before the battle, Ash and his friends are speaking to Roark, where it is revealed that Roark is there to convince his father to come home to Oreburgh City for his parents' anniversary. A flashback is shown, in which Byron leaves Oreburgh for Canalave City, since the Pokémon League asked him to take over the Gym there. He also states that Iron Island will be a good place for him to find more Fossils. He leaves Roark in charge of the Oreburgh Gym where he was formerly the Gym Leader. He also leaves his wife behind in his move. Brock mentions that this reminds him of a father he knows.
Roark starts the fight by having Rampardos repeatedly using Zen Headbutt, while Byron instructs Bastiodon to counter with Iron Defense. Ash notes how powerful Zen Headbutt looks, and Brock replies that he thinks Byron actually has the upper hand. Byron instructs his Bastiodon to use Flamethrower, which Rampardos dodges.
Meanwhile, Team Rocket has dug a hole into Byron's Fossil collection. James and Meowth recognize how valuable the Fossils are and the group decides to steal them.
Back at the battle, Roark has Rampardos use Head Smash, which Byron combats with Iron Head. Roark then has his Rampardos use Flamethrower and Byron counters with Flash Cannon. After the collision, Bastiodon seems to have the upper hand. All of a sudden an alarm goes off and Byron calls off the battle to go check on his Fossils. Upon entering the Fossil room the first thing Byron notices is how expertly Team Rocket dug their entry hole and doesn't even notice that his Fossils are missing. He then goes on to talk about Team Rocket's escape hole which he concludes must have been dug by a machine. Roark has to point out that all of his Fossils are missing before he notices. The group then jumps down Team Rocket's escape hole in an attempt to retrieve the stolen Fossils.
At the other end of the hole, Team Rocket is seen emerging with a drill mecha carrying the Fossils. They begin to walk away when Byron, Roark, Ash, Brock and Dawn peek their heads out from inside the hole. The group confronts Team Rocket. Team Rocket does a modified version of their motto. After they finish Byron begins a speech where instead of getting mad at them for stealing his Fossils he tells them they should only dig their holes by hand and not use machines. Roark points out to him that these are bad people who stole his Fossils and Byron doesn't believe that such good hole diggers could have taken his Fossils. Team Rocket then admits to stealing the Fossils.
Roark sends out his Rampardos and Byron sends out his Bastiodon in an attempt to get the fossils back from Team Rocket. They attack the mecha, which takes almost no damage. Meowth, who is controlling the mecha, then has it start throwing chunks of earth at Rampardos and Bastiodon. Roark instructs Rampardos to use Zen Headbutt on the mecha. It is stopped by some of the chunks of earth that are being thrown at it by the mecha. The mecha then picks up some larger chunks and throws them at Rampardos. As it seems Rampardos is about to be seriously hurt by the tossed chunks of earth Byron has Bastiodon jump in the way and use Iron Defense which blocks the chunks of earth. Byron tells Roark that his is why he wants Roark to worry about defense more. He then tells Roark to have Rampardos use Head Smash. The attack knocks over the mecha and Ash then has Pikachu use Thunderbolt. The mecha appears unaffected and gets back on its treads. Meowth says the Thunderbolts can't hurt the mecha but he is a little worried about all the head butts. Team Rocket begins to leave and Roark and Byron have their Pokémon use Head Smash and Iron Head respectively. The attacks create two small holes in the back of the mecha. Brock then suggests to Ash that he have Pikachu use Thunderbolt on the holes in the mecha. Ash does and the mecha explodes sending Team Rocket blasting off. The Fossils were also launched but not as far and as they fall back down near the group Roark and Byron are both worried about the safety of the Fossils. After they have landed the pair goes to make sure they are safe. Roark says they are all safe.
Byron then shows Roark his most prized Fossil, a Fossil of a Sunkern leaf. A flashback reveals that the SunkernFossil was found by Roark as a child, being the first Fossil he ever found, and that he gave it to his father. Back in the present, Byron and Roark make amends. Dawn tells Ash and Brock that seeing Roark and Byron making up makes her miss her mother. Brock tells Dawn he was thinking of giving his family a call since it was long overdue, and Ash agrees that he should phone his mom too. Byron then tells Ash that he is sorry he has kept him waiting for his Gym Battle but he will have to wait longer as his Bastiodon needs time to rest. Ash agrees and the Gym Battle is scheduled for the next day.
The legend of the sharpest spear that could break any shield, and the strongest shield that couldn't be broken, is referenced in the battle. This parallels the irresistible force paradox in Western philosophy.