Yes, of course you can use GG with the Everdrive MD.
Here is what I find works with my EDMD:
1. Load up the game you wish to play
2. After game is up and running, turn off and re power to the EDMD screen.
3. Scroll down to enter codes option
4. Pushing "A" gets you into each menu/submenu. "B" backs you up one level
5. Enter the GG code. (I can only enter one code at a time on mine.) After the code is entered, push "A" and the EDMD should say, "ROM Patching". You can tell when it is finished doing so when a number appears in the upper left hand corner of the screen. (0 or 21 on mine) You can now push "B" to back up and enter another code or back up to the "play game" screen.
6. Select "play game" and your game should start with GG codes active.
*If game won't run, then GG codes are messed up. Happens a lot! I usually start with one code at a time, that way I know exactly which code works. Sometimes a master code is required which is not listed, but you can often Google a MC for a specific game. Also: Just because a game won't run initially, doesn't mean all is lost: Reset the Genesis; sometimes this will cause everything to come up normally with the code(s) active. If it doesn't, back to the drawing board.
** If you get a bad code, don't just go back and re-enter more codes. Reload the original game first. (Steps 1 and 2) This way, you ensure starting with a clean copy that hasn't been erroneously patched. Otherwise, you are just patching an already 'broken game".
Hope that helps.
