How do I transfer save data from standalone Dolphin to the libretro core version?
You might try just renaming your Dolphin save to gamename.srm (make a backup first, of course). When possible, we keep the save files identical to the original emu’s for this reason.
…where do you get the Dolphin saves to begin with?
Dunno, I don’t use standalone dolphin.
Dolphin saves GameCube game saves as a single memory card file “ie MemoryCardA.USA.raw”, one for USA, another for JAP and another for EUR. They’re in the Dolphin/User/GC folder, filetype .raw. Copy these into your RetroArch/saves/User/GC folder. DO NOT change the file type.
Wii saves are saved as individual files by dolphin, I believe, and I think those will be in Wii folder. I cannot confirm because I don’t have any Wii games as of yet.
After a lot of digging, I was FINALLY able to figure this out. What I ended up having to do was use standalone dolphin’s memory card manager to export a .gci and put that in retroarch’s gc save. More specifically, in the memory card manager, I opened %HOMEPATH%\Documents\Dolphin Emulator\GC\MemoryCardA.raw and exported the gci to %HOMEPATH%\AppData\Roaming\RetroArch\saves\User\GC\USA\Card A\
You can open Dolphin’s memory card manager by running dolphin and clicking tools > Memorycard Manager (GC)