Friends
Friends (Japanese: なかま) is a category in the Toys (Japanese: ずかん, Picture Book) feature in Densetsu no Starfy 4 and The Legendary Starfy that lists most of Starfy's friends and acquaintances, as well as Starfy and Starly themselves.
In Densetsu no Starfy 4, Tobira Majin and King Tobira Majin and the residents of the Amy Kingdom other than Mattel are not listed in the Picture Book at all. Additionally, Kujira Papa and the Kujira Children are listed with the enemies rather than under Friends, probably because they are found in Area 1 of Thousand Year Hill itself.
In games prior to Densetsu no Starfy 4, Characters are listed in the Picture Book or Trading Cards (Densetsu no Starfy 3) in the Stage category, meaning that they are found with Enemies. Fork used to be classed as an enemy but he was reclassified as a Friend in The Legendary Starfy, presumably because he is an interactable character in that game who plays with Starfy in the Race with Fork and Shuffle Fork Side Quests and cannot be defeated.