Stuff (Japanese: グッズ, Goods), as its known in The Legendary Starfy is a tune in The Legendary Starfy and Densetsu no Starfy 4. In Densetsu no Starfy 4 it's known as Goods Screen (Japanese: グッズガめん). It plays on the Stuff (Goods) menu where Starfy and Starly dress up.
Sounds different to the theme from Densetsu no Starfy 4. It's the sixty-seventh track in the Sea Jams.