Why can't they be emulated? I'm guessing they could, as I think anything can be emulated. Maybe whatever you're talking about hasn't been emulated yet because coders haven't got access to the hardware documentation, which I'm sure Nintendo Would . Also, what does this have todo with Multiplayer???.some games need special chips that the original hardward provided, some of these chips cannot be emulated.
Like I have already said... "you would have the ability to play any physical multiplayer games online".The game that your playing also needs a "VS" option to begin with.
I have no idea of what you mean...Also, the Emulator has to be configured to emulate the game properly for online to work, it also has to be configured to play with other systems or emulators.
Finally... I have tried using various emulators online. Most emulators go through the sucky/laggy Kaillera Servers, mainly for systems with more than 2 players. I liked ZSnes/ZBattle best, as players are connected directly to each other, and so there is minimal lag .