

If declined linking it, it won't work for online. When choosing that account as the 2nd player for Diablo online, the game forces the author to link it to a Nintendo account (presumably to check for online subscription). The author made a new guest account and didn't tie it to an account.The author said it doesn't matter if the 2nd player's account/profile was tied to another Nintendo account.The author tried out the same thing with Mario Kart 8 Deluxe, and noted that "you can play 2 player on 1 switch online, with just 1 online subscription." But, this has been pointed out that this is offline local multiplayer, which is allowed.However, the author attempted to play locally with a 2nd player (on 1 switch), and found out the game is unable to go online with that 'user account', as it doesnt have online access.The author has read about the game that it would require the Nintendo Online Subscription to play online.
