Ok, so I finally found the solution by doing a little more web searching. This “should” help anyone experiencing issues setting up their controller(s). Disclaimer: so far I’ve only been able to set up 1 player with my X-Arcade tankstick, but it’s start. All credit goes to user, hoechst, on this thread (2nd post down):
His post will explain how to assign the correct key values to your controller and what ID is assigned to it. I will recommend that anyone who’s been altering the emu.cfg and controller mapping file, should delete all the reicast emulator files from RetroPie and reinstall from Source Binary. to start with a fresh install.