Nintendo never added the ability to queue up with a friend in Splatoon 2, a TEAM BASED SHOOTER! I have no hope that the majority of the baffling design choices in Smash online will ever be changed.
Me and a friend spent a few hours trying to team up in Splatoon one day and couldn't figure it out, we thought we were just being dumb. Sometimes we'd get into a game together, but most of those times we'd be on opposite teams with one of us getting dropped at some point. That was back in July, neither of us have tried again since.