I just got my Retropie Up and running, and I am playing Pokemon Red. when I use TGB-Dual to launch the Rom, I cannot load my savings in the second screen.
Did anyone manage to make the link in tgb Dual work to trade Pokemon?
I don't think it's possible in retropie from the answer I found here: http://libretro.com/forums/showthread.php?t=6507&p=43843#post43843
As a workaround, I took my save file, renamed it to a .sav, and then used TGB Dual 8 on a PC to trade. Then renamed save file to .srm and moved back to retropie. It's a pain but it was worth it for the Gengar!
This guide was also useful for TGB Dual: https://forums.emulator-zone.com/showthread.php?t=22770