File:Official Tourney Qualifiers Japanese Menu Item.png

Summary
So the Japanese Version of the Mode has a built-in online Mode.

Source of the image is here: https://www.smashbros.com/ja_JP/tournament/index.html

More information on this mode can be found in this reddit post: https://www.reddit.com/r/smashbros/comments/id4e1k/japan_has_an_entire_online_ladder_mode_that_we/