I have an old Raspberry Pi 1 (!) still going strong with Batocera Linux running NES, SNES and Mega Drive (Genesis) emulators.
I’m looking for easy multiplayer games that can be played with a 5yo. Non violent and ideally co-op, bonus points if somewhat educational.
Sonic 2.
Controlling Tails can be good fun if you’re very young and don’t fully know what you’re doing!
Can be hard keeping both characters on screen at times though.
Actually Sonic 3 is a slight improvement in this regard once you get the hang of things - Tails can be more helpful, and carry Sonic to higher ledges