Game ID: G-3356
Package ID: 671-5341
Cartridge ID: 670-5434
Sonic & Tails 2 for Game Gear was released on November 11, 1994 in Japan. It is known outside Japan as "Sonic the Hedgehog - Triple Trouble".
TIPS AND TRICKS
Level select: This is a bit tricky, but it works. Hold at start Up and then, during the intro, press START exactly when Knuckles touches the third emerald (the red one). A ring sound will confirm the code and, when you start the game, the Select Stage screen will appear after the Stage Character one.