What episode does ash battle cynthia?

In the Pokémon anime, Ash battles Cynthia in two episodes: "Battling the Unbeatable" and "Enter the Champion!". The first battle takes place in the Sinnoh League quarterfinals, while the second takes place in the Sinnoh League finals. In both battles, Ash is defeated by Cynthia, but he learns valuable lessons from each experience.