Mother of All Battles (Japanese: バンギラスとヨーギラス！ Tyranitar and Larvitar!) is the 55th episode of Pokémon: Master Quest.
After finally arriving at Mt. Silver, Ash and co. find the Preserve where Larvitar was born. There they encounter Larvitar's mother, the same Tyranitar that was in Larvitar's visions. The reunion was not a happy one however, even after they get reunited. The three men from Larvitar's visions were also the ones responsible for stealing the Larvitar Egg and they managed to capture the Tyranitar. Can they get mother and child reunited with the help of Ranger Mason?
When the heroes finally get to the Pokémon preserve where Larvitar was born, Larvitar is very happy. Misty remembers the first time she met the Larvitar, how it used to harden at the slightest thing she ever said. Brock then says that the Pokémon preserve should be near them but he doesn't know which side of the bridge it is on. The Larvitar suddenly jumps out of Brock's hands and runs over the bridge. The bridge is over water and the screen goes to a camera that is poking out of the water. The gang has crossed the bridge and follow Larvitar through a forest to the preserve owned by Ranger Mason. Three men observe the heroes and think about capturing the Larvitar, Pikachu and Togepi.
Suddenly a Tyranitar comes. Ash notices a scar, so they know it is Larvitar's mother. Larvitar stands still and Ash gives it a little push, telling it to go to its mother. Tyranitar gets angry and shoots a powerful attack at Ash, Brock, Misty, Pikachu and Togepi. Brock thinks that it got angry because Tyranitar think they stole the egg. Tyranitar attacks again but Ash and Misty try to make it understand that they are trying to help. But Tyranitar does not listen and starts to chase Ash and the gang. Larvitar follows them and cries. Ash tries to tell it to go back to its mum but it holds onto Pikachu's tail. The three men are inside the machine and they try to keep the Tyranitar in their sights.
Ash and friends are being chased and Ash tries to get Larvitar to tell Tyranitar that they are its friends. But Tyranitar shoots another powerful attack that knocks them all over. Larvitar falls at its mother's feet and it starts shouting loudly. Tyranitar then understands and smiles at Larvitar. Tyranitar is captured inside the Poké bag and falls over. Tyranitar tries to attack the bag but there is a part of the bag over its mouth. The machine comes out from the bushes and in front of Ash and the gang. The gang remembers that these three men were the poachers that stole Larvitar's egg. They reveal themselves to be the Pokémon poacher brothers. Jessie, James and Meowth have been watching the whole time. Jessie comes up with the plan that they should tell the poachers that they want to join them and then eventually steal all the Pokémon they caught.
The gang and the poachers are about to shoot another Poké bag but this time at Larvitar. Ash tries to stop it but ends up jumping in front of Larvitar and the bag catches him instead. The poachers then hear a sound and know the preserve rangers are coming, they grab the Tyranitar using their machine and speed off. Brock sends his Crobat and tells it to follow them. Ranger Mason and her Croconaw then comes on a motorbike and Brock jumps at the chance to talk to her. Then Misty tells Ranger Mason what has happened when she realises that they are here to bring back the Larvitar. Brock then boasts about how he told his Crobat to follow them to their hiding place. Ranger Mason then sees Ash in the bag and after a while he is out of it. Team Rocket is trying to team up with the poachers at their hiding place. The poachers accept but Crobat is listening and then flies off to find Brock. The poachers tell Team Rocket to capture Pikachu and Larvitar and they let them use their machine with the Poké bags in.
The poacher boss reveals his plan to use Team Rocket as a distraction to the Pokémon Rangers for them to make their getaway with Tyranitar. Crobat found Brock, while Ranger Mason tells Crobat to lead the way to the poachers hideout. On their way to the poachers hideout, they meet Team Rocket., who reports how they teamed up with the poachers. They then launch a Poké bag at Pikachu, though Ash then tells Pikachu to use Thunderbolt and Ranger Mason tells her Croconaw to use Hydro Pump. And they force the bag to shoot towards Team Rocket. This makes them blast off again. Three poacher brothers are in Team Rocket's Meowth balloon, looking at Ash and the gang. One of the brothers activates the machine and it comes to life, its hands reaching out and grabbing Ash's Pikachu and Ranger Mason's Croconaw. Then the machine shoots a bag at all the gang except Larvitar who is left watching in shock. Ash then tells Larvitar that its up to itself to save its mother and he tells it to use its powers.
Larvitar then starts shouting, making Tyranitar open its eyes and start struggling to get out of the bag. It shakes the bag and ends up shaking the balloon to which it is attached to. Because of Tyranitar using small hyper beams to slowly damage the bag, one of the brothers presses a remote which makes an electric shock run through the bag. It hurts Tyranitar, but despite the shock, It manages to break the bit of the bag that covered its mouth to stop it from attacking. Then it uses Hyper Beam to burst the balloon. The bag is released from the balloon and the balloon, along with the Pokémon Poacher Brothers, descends down.
One of the brothers dropped his remote which is smashed when it hit the ground, and this releases the gang and Tyranitar from the bags. The poachers get out of Team Rocket's balloon and into their machine and speed towards the gang. But Tyranitar and Larvitar respectively use Hyper Beam and Hidden Power which impacts the machine and it explodes, Pikachu and Croconaw are flung into the air but they are both caught by Ash and Brock, though the latter gets squashed by Croconaw. The poachers are tied up and Ranger Mason and the other rangers are thanking Ash, Misty and Brock for all that they've done. Larvitar and Tyranitar also say goodbye as well. Ash, Misty and Brock then head to Silver Town for their next adventure. Meanwhile, Team Rocket is hanging on the bridge, still in the bag.
The "Who's that Pokémon?" is Shuckle.