In a Tweet from Nintendo of Europe, it has been confirmed that an update will be releasing on December 1st that will be adding queuing with friends in online and Doubles play online!
This is the first time you will be able to play in a team with your friends online in Mario Tennis Aces!
A new update is coming to #MarioTennis Aces on 01/12, adding doubles play to online tournaments!
— Nintendo of Europe (@NintendoEurope) November 27, 2018
The update will let you do online doubles play from: one console or even on 2 consoles even a internet connection!
Once we have more information to share on Mario Tennis Aces we will post it here so stay tuned!