During the Super Mario Maker 2 Direct from the other month, we found out that the title would allow players to play with or against one another online. A few days later during a preview event, a Nintendo representative claimed that the feature would only match you with random players, with no option to play with friends.
Contrary to this however, Super Mario Maker 2 director, Takashi Tezuka, confirmed that they are working on an update to be published post-launch that will add the ability to play with friends online. This was revealed during the Nintendo Treehouse Live today at E3 2019.
Super Mario Maker 2 launches exclusively for Nintendo Switch on the 28th June 2019