Super Mario Maker 2 boasts a strong online component that includes sharing custom maps online, time trials, and co-op. But despite a litany of features, Super Mario Maker 2 doesn't appear to have more common features like matchmaking online with friends.
Nintendo World Report confirmed that Super Mario Maker 2 matchmaking with friends online for either co-op or competitive play will not be doable. Instead, to play with friends you'll either need to play locally on a single system, or connect via local co-op.
What this means essentially is that players will only be matched with other random players online if they want to participate in time trials or co-op play. It's a strange feature omission that nonetheless highlights some of the idiosyncrasies with the Nintendo Switch Online subscription service.
In Super Mario Maker 2, players can create and share custom Mario levels online. A new feature in Super Mario Maker 2 is that these custom-created maps can enable co-op play online. They can even allow for competition like timed races to see who finishes a course first.
According to NWR, Nintendo says that because of the global leaderboards "the matchmaking for competitive play would be compromised if you could play with friends." Oddly enough, co-op doesn't have leaderboards but is still barred from matchmaking with friends.
As it stands, the only option in Mario Maker 2 online is to play with random players. You'll still be able to share maps with your friends or play their maps through map codes and the social follow feature, but playing together is pretty much off the table.