RetroGaming

Most of the old consoles it can be done. I've played a bunch of games this way. The most fun I had was probably Kirby Super Star on the snes.

But it's possible with the newer consoles too. The buzz word is typically "netplay". Works by syncing the game state and emulating their controller being connected with the host session and vice versa.

Depending on the specific game or emulator you're trying there can be some pitfalls. Some emulators won't let you play unless the application is identical and identically configured (such as the various plugins in 1964). You would need to run the same windows version of the emulator to play with your buddy likely.

Network quality is extremely important. No one should be using WiFi. All players ideally should be using low jitter connections like fibre, cable or dsl. Ideally your ping to each other is under 60ms. Once you get into the 80-120+ range PvP games become unfair and games in general could become glitchy.

Have everyone playing run this tool. You're looking for low jitter, medium to low ping, 0% packet loss. (It just isn't going to be reliable and fun if anyone is experiencing any packet loss)

https://speed.cloudflare.com/

Depending on the emulator you might need to understand port forwarding and resolving a double NAT.

If you want to discuss what specifically isn't working I could be more helpful instead of sharing generalised information.