Nintendo says they will put out a free rental virtual console game for each month that has online multiplayer. No one is asking what type of games Nintendo would put up.
The biggest 16-bit multiplayer games already have Switch incarnations. Street Fighter 2 and Bomberman have their Switch version so I doubt it would be those games. Mario Kart is already represented too.
It wouldn’t be a licensed game like a cartoon show or something with Tetris in it (e.g. Tetris Attack) or Teenage Mutant Ninja Turtles (owned by Konami)
The multiplayer games are rather limited and seem restricted mostly to co-op.
Super Dodgeball. Jackal. Contra. Life Force. Snow Brothers. Marble Madness. Ice Hockey. Mario Brothers. Zombie Ate My Neighbors. NBA Jam.
Yeah, there are many more, but I am trying to think of what Nintendo would think is a good idea to demo for their new service. My bet is that they will do Ice Hockey or Zombie Ate My Neighbors.