S8E45 : Hooked on Onix

On their way to the Battle Arena, Ash and his friends take a break to rest. When they run out of water, Ash, May, and Brock go to look for some while Max stays and feeds the Pokémon. When Munchlax eats everyone's food, a battle ensues, which angers some nearby Geodude who, in return, attack the Pokémon. Pikachu, Corphish, Phanpy, Squirtle and Munchlax get separated from the group. Meanwhile, Team Rocket convinces an Onix, who is the king of the Rock Pokémon, that Ash and the others are evil and Onix sends its Rock-type army to capture them. Unknown to the Rock-types, Team Rocket wanted to use them to help steal Pikachu and the other Pokémon.