All Gameboy games (as far as I'm aware) have batteries inside the cartridge, the saves were stored on volatile memory and were battery-backed. Gold, Silver, and

All Gameboy games (as far as I'm aware) have batteries inside the cartridge, the saves were stored on volatile memory and were battery-backed. Gold, Silver, and Crystal just made extra use of the battery with an RTC. I can find many instances across many forums of people talking and troubleshooting replacement batteries for their Red cartridges so I don't believe my memory is failing me here.