I downloaded the latest stable Windows 64-bit binary + according cores:
RetroArch-v1.0.0.2-64-bit.zip Cores-v1.0.0.2-64-bit.zip
However, the Jaguar core is not included. Did Libretro abandon it or do you have to download it somewhere else? On the web I saw people claiming to play Jaguar with RetroArch, so I thought a Jaguar core exists and is included.