There are plenty of options when playing online in the upcoming Super Smash Bros Ultimate which will require a Nintendo Switch Online subscription. You are ranked with GSP Scores and choose who you play against. Matchmaking will prioritize based on location so you’ll be playing against people near you. Elite Battles have been announced which is the highest ranked mode. You can send short messages that are preset against your various opponents and match making can run in the background. You can also have two players online on same system against a team against others. You can also voice chat using the Nintendo Switch Online app on your phone. There’s also Smash World which is a separate app which logs your progress.