Previously, we’ve reported that Splatoon 2 will allow up to eight Nintendo Switch systems to connect via local wireless to play Private Battles. In addition to this, a new feature called LAN Play will enable players to connect eight docked systems using a wired LAN setup. This feature allows players to create local Private Battle tournaments without the need for an Internet connection.
If you’re willing to put in the work to set up LAN Play, you can also use the Private Battle Spectator View feature by hooking up two additional Nintendo Switch systems. Local wireless play is perfect for your regular gaming get-togethers, but LAN Play is where it’s at when you want to organize a serious tournament event with your fellow players.
— Squid Research Lab
Source: Splatoon’s Tumblr.
…Don’t have an NNID? Buy a Wii U.
Well… not anymore. Anyway, click on Splatoon 2 for everything you need to know about the game. 😀