Wall Jump
From Starfy Wiki
Wall Jump (Japanese: かべじゃんぷ) is an ability only Starly can use. To use it in The Legendary Starfy, press the B button near a wall. Press the A button for Densetsu no Starfy 4 and the Game Boy Advance games. It is taught to her by Kittana in Densetsu no Starfy 3, then by Shurikit in Densetsu no Starfy 4. Starly does not forget how to use it in The Legendary Starfy.
Description from The Legendary Starfy
"Face a wall and jump! When you hit a wall, jump again to get more air."