-Gameboy (GB), Gameboy Color (GBC) games were tested with the console and both work as intended
-All buttons (Dpad, A & B, Start & Select) have been tested and are functional
-Headphone jack has been tested and is functional
-Volume wheel has been tested and is functional
-Power slider has been tested and is functional
-Speaker has been tested and is functional

-Link port has not been tested, therefore it is untested. Physically, the port looks well.
If you have any question, ask before bidding/purchase.