Densetsu no Stafi: Taiketsu! Dire Kaizokudan
This game is titled The Legendary Starfy in North America and Densetsu no Stafi: Taiketsu! Dire Kaizokudan in Japan.
Successfully complete the game by finishing World 8 to unlock the "Sound Test", "Gachapon", and "Boss Mode" options as well as World 9. To access the new options, press R at the level selection screen.
Successfully complete Boss mode (Big Bossdown) with either Stafy or Stapy with a time less than 9:00. World 10 is a series of time attack levels that includes a new Boss. To face the new Boss, you must complete level 10-1 with a time less than 0:45, level 10-2 with a time less than 2:20, level 10-3 with a time less than 3:50, level 10-4 with a time less than 2:10, level 10-5 with a time less than 2:50 and level 10-6 with a time less than 2:30.
Successfully complete the game two times.
Play on your birthday to see a new introduction screen.
Go to Hotcha Springs (level 2-1). Get to the part where there is a little rock below the door you just entered, little white fish to the top left corner of the stage that inflate when you touch them, and a line of fish to each side of you. Start by going to one line of fish and using the spin attack to take out the line of them, then go to the other side and take out that line. Keep repeating this, going from one side to the next, until you get as many pearls as desired.
Super Mario World reference
The background music of the "Abilities" screen is the music from the Special World of Super Mario World.
Strategy guides from GameFAQs