Pokémon : S21 | E40 – Dummy, You Shrunk the Kids!

The Pokémon School has a visiting teacher: Faba! When he shows off his invention that can reduce the size of objects for easy storage, it malfunctions and Ash, Lillie and Sophocles are shrunk to tiny size! Faba recruits Rotom Dex to help him repair the machine and meanwhile, our heroes are thrown into a world where everything is gigantic. They eventually reunite with Pikachu, who sneezes on them—causing them to return to normal size. But just when Faba thinks he's fixed his invention, it misfires again…and the result is a towering Togedemaru! (Source: Wikipedia)