You can connect any controller, including the old Joy Con or Game Cube controllers, to Nintendo Switch 2 at any time, simply search under Controller. Works perfectly for all games unless you need the mouse function, which of course only works with the new one. But who needs the mouse control?

The Nintendo Switch Pro Controller is compatible with the Nintendo Switch 2, but cannot be used for games that require specific functions of the Joy-Con 2. However, you can use it for many games that are available on the Switch 2.