I went through and made game remaps for most (if not all) of the 4 Way Play and Team Player (multi player adapters = enabled by default) for the Sega Genesis. It was quite a task - changing a setting many times didn’t work, so you’d have to save a game remap first, exit, then restart. And, some games need 3 buttons specifically, and some of them need the adapter to be in port 1, and some of them need to be in port 2.
It was a good 10 hours of work to get 80 games working. The remaps are named after HyperSpin database XMLs (similar to No Intro). Includes Sega CD games.
The default controls are (xbox button = genesis button) A=A, B=B, R bumper = C, X=X, Y=Y, L bumper = Z, Right trigger = mode (like it would be on a real 6 button Genesis controller).
If those default controls don’t work for you, and you’re handy in the fine art of file manipulation via ‘find and replace in all files’ with notepad++, have at it.
Instructions: unzip all of the files to \RetroArch\config\remaps\Genesis Plus GX (or wherever else you put your remaps)
Not sure how useful something this specific may be but it was a lot of work and if I don’t share it, it was a serious waste of life. So, enjoy.
https://drive.google.com/file/d/0BwsItKU19h3leENPSmpsb2xSYmc/view?usp=sharing