Jumping (Japanese: じゃんぷ) is one of Starfy and Starly's most basic techniques. Jumping will launch Starfy or Starly into the air, allowing them to reach higher places. To jump in The Legendary Starfy, press B. To jump in Densetsu no Starfy 4 and the Game Boy Advance games, press A. The Air Jump ability, once learned allows Starfy to jump in the middle of the air.
Description from The Legendary Starfy
"Sail over the heads of any nearby bad guys with this jump."