The first appearance of the "Wanpaku Trio" (Yo-chan's triplet brothers). In this episode we not only learn their individual names, but also the origin of their feud with Cub.
25 years before Tom Hanks would fall in love with a volleyball in Castaway, a young boy named Akira finds acceptance among his classmates when he discovers a talking ball that enables him to never miss a shot.
This is the episode where Gorem (Krag) replaced Kiritobi (Warlock) as the series' main recurring villain. Kiritobi made just one more appearance after this, his final battle against Aji Baba in the second to last episode.
Here's a two part story where the Japanese Yokai (including the first anime appearances of Ittan Momen and Nurikabe) square off against a group of Western Yokai.