It’s been revealed today that those of you who wish to play online with your friends in Super Mario Maker 2 will need to play on one system locally or through the game’s local wireless play. Playing Super Mario Maker 2 online only allows for random match making. A Nintendo representative explained to NWR the reason behind this decision:
Nintendo’s reasoning is that, with global leaderboards, the matchmaking for competitive play would be compromised if you could play with friends. That limitation also extends to co-op play as well despite those not being leaderboard driven.