Pokémon : S5 | E51 – A Crowning Achievement

Ash and Pikachu run ahead, but end up sliding down a steep hill. His rough ride ends when he hits a boulder. Misty and Brock soon catch up and notice that they have arrived at the lake’s supposed location. However, it appears to be a dried-up stream, surrounded by a number of thirsty Slowpoke. Ash and friends spot a King’s Rock, but are stopped from approaching it by Alice, her father Professor Telesu, and her Slowpoke, nicknamed Arthur. Brock promptly falls in love with Alice, but Misty drags him away. Alice explains that she and her dad are researching legends surrounding a supposed Slowking who could help save the colony of Slowpoke. She explains that the lake dried up because an earthquake opened a fissure that drained most of the water, and insufficient water flows in from the river to fill it again. Professor Telesu leads them to a cliff with runes carved into it. The cliff face and the King’s Rock only appeared once the water receded. Telesu explains that a special Slowpoke is destined to save the colony, by reaching the King’s Rock to evolve into a Slowking. Misty notes that the legend is very similar to the events happening now and Telesu explains that only one panel eludes him. Ash notes that it looks like a rainbow with a comb on it.
(Source: Bulbapedia)