A Crowning Achievement (ヤドキング！おうじゃのしるし！ Slowking! The King's Rock!) is the 51st episode of Pokémon: Master Quest.
While enroute to Mt. Silver, Ash and co encounter even more Slowpoke and a King's Rock on a stalagmite. As they were about to investigate it, a young researcher stops them. She and her father explain that that rock is to crown the next Slowking, but the rock is guarded by Shellder. Will Alice's Slowpoke be the next king?
Larvitar wakes up and Misty tells she thought Ash was the only one who is always sleeping. Larvitar is shy, so Ash replies Misty she is always picking on it, then tells Larvitar it saves up its energy. Brock tries to cheer it up making grimasses, but this causes Larvitar to screech out. Ash calms it down, but Brock is confused, as his faces always make Pokémon laugh. He advises they could go to the waterfall and have lunch, which Misty, Ash and Pikachu agree to. As James and Meowth plan on stealing Pikachu, Jessie eats their lunch and goes after the twerps, displeasing James and Meowth.
Ash runs with Pikachu, but accidentally falls down a slope. After getting hit, Ash, Misty and Brock notice the waterfall, but the river is dried up, while the Slowpoke do not seem happy. The heroes go to check out the King's Rock on a boulder, but two people stop them, as that is the Slowpoke's hope. The heroes promise they will leave the King's Rock, pleasing the two people, who are Alice and her father, with their Slowpoke, Arthur. Brock tries to give an impression, but Misty drags him away. Alice and her father go to show the heroes something with the King's Rock. Team Rocket is also interested in capturing that artifact.
Alice believes her Slowpoke, Arthur, is exhausted, but Arthur shakes its head. Her father tells the heroes Slowpoke was her Pokémon since it was small. The heroes notice the lack of water and Alice responds this used to be a large lake. However, an earthquake caused the water level to drop, causing Slowpoke to suffer. However, Alice's father shows the heroes that the water level drop revealed a carving in the wall, the legend of Slowking. He believes that the Slowpoke nearly vanished from the lack of water, but a Slowking changed that and saved them. Ash thought Slowpoke can only evolve into Slowbro, but Alice's father tells they can evolve into Slowking with the King's Rock. Misty sees the story is similar to the situation today. Alice's father tells it is what it makes the situation exciting, but he sees the last panel is symbolizing a Slowpoke paradise, but does not understand the panel before it.
Ash thinks that symbol looks like a rainbow with a comb, making Brock and Misty unamused. Suddenly, Team Rocket appears in a royal theme, wanting to take the King's Rock. Jessie sends Arbok and James Weezing to take the King's Rock. Pikachu goes to protect it, dodging Poison Sting. Pikachu uses Quick Attack, but misses and gets hit by Arbok, who goes to bite. However, Larvitar screeches, distracting everyone but Arthur, who is not bothered by the sound. Team Rocket goes to take the item, but trip over by Forretress' Rapid Spin, then blast off by Pikachu's Thunderbolt. Alice and her father are grateful, but are still worried that the river might dry out. A Slowpoke tries to take the King's Rock, but like the rest, a Shellder bites its tail, causing it to evolve into a Slowbro.
Alice is very sad, thinking what might happen to Slowpoke. Suddenly, Arthur moves to take the King's Rock. Brock thinks that is its duty, but worry that Shellder will come. However, Arthur dodges the Slowpoke, but falls in the water. The Shellder track it down, but Slowpoke uses its tail to swim away. Arthur comes to the boulder, but Shellder ambush it. Larvitar screeches again, causing everyone but Arthur to be distracted. Arthur places the King's Rock on its head, but a Shellder bites the King's Rock. Nevertheless, Arthur evolves into Slowking. Team Rocket appears again in their balloon, wanting to take Slowking. They throw a net, but Slowking uses Confusion, causing the net to wrap the balloon.
Meowth releases a smoke so the twerps cannot see them, but Slowking uses Confusion, blowing them away to a cliff, causing them to fall down. The Shellder bite their lower part of their backs, then Team Rocket blasts off by Pikachu. The heroes, Alice and her father, remember that Slowking would show the Slowpoke paradise. Ash worries, as Arthur might not know where to go. Arthur releases an energy, parting the waterfall into two flows, revealing a cave, which is the symbol of the Slowking legend. Arthur leads the Slowpoke, as well as the heroes, into the cave. Arthur led them to a large lake, bustling with beauty and space. Later, Alice parts ways with Arthur, since Arthur must lead the Slowpoke. She asks never to forget her and bids farewell to it.
The heroes think it is still great to have a king for a friend, plus she can always visit him. Later, Alice and her father promise to watch over this paradise. Brock still tries to make an impression, but Misty pulls him away. Ash goes with Misty and Brock, saying farewell to Alice and her father.
- This was the final episode in the entire series that used hand-colored cell animation. Every episode after this from JE145 onward uses Digital-colored cel animation.
- The "Who's that Pokémon?" is Kadabra.
- Slowking Arthur is a reference to King Arthur.