The Unbeatable Lightness of Seeing! - S9.E40

Ash is still recovering from his defeat at the Battle Pyramid, while May is also melancholy about her own defeat at the Grand Festival. Professor Oak shows up at the Pokémon Center in Fennel Valley, with a special care package meant to cheer Ash up. It contains a poster with the prints of his Pokémon, a fishing lure from Misty, and food from his mother. There's even a postcard from Gary in Sinnoh, which gets Ash thinking about their rivalry and actually pulls him out of his funk.