Pokemon: Bokutachi Pichu Brothers - Party wa Oosawagi! no Maki

The Pichu Brothers learn that Meowth is throwing a huge party, but they and their friends appear to have been left off the guest list. Hurt and curious, the group gets pulled through a series of small mishaps as the celebration approaches.

Eventually they discover that the problem was not rejection at all: their invitations simply arrived late. With the misunderstanding cleared up, the Pichu Brothers finally join Meowth's lively gathering, where the long-awaited party proves every bit as chaotic as expected.