https://www.cnet.com/news/nintendo-switch-online-will-bring-new-multiplayer-options-for-mario-bros/

Nintendo teased online multiplayer functionality for the original Mario Bros. as part of its Switch Online service.

Even if players aren't in the same room, Mario and Luigi will be able team up to take on the Koopas invading the sewers of New York City when the 1983 classic arrives as one of the 20 free NES games for subscribers of the service.