The only way to access stage select is by using a Game Genie or other similar hardware device that allows you to modify the game's code.
Here's why you can't access stage select through regular gameplay:
* No in-game option: Sonic 2 doesn't have a stage select option built into the game's menus.
* No specific cheat code: No combination of button presses or specific actions can activate stage select in Sonic 2.
If you want to play specific levels, you can:
* Use a save state: If you're playing on a console with save state functionality, you can save the game at the start of a level and reload it to play that level again.
* Use a Game Genie: As mentioned above, using a Game Genie or other hardware device can allow you to access stage select.
* Play a ROM hack: There are ROM hacks of Sonic 2 that add stage select options.
Remember that using Game Genies or ROM hacks may not be considered "legitimate" gameplay, but they can be a fun way to experiment with the game!