The name for the tournament feature is “Friendly competition”. There are two modes to this feature, a “Live” mode, and an “Online” mode.
The Online mode allows you to join ladder tournaments created by other players with a specific ruleset. These tournaments will be similar to the special tournaments run on Global Link every once in a while, such as the Alola Friendly of recent. These allow you and many friends to play in formats that may not exist otherwise. Be aware that for one of these tournaments to run, a minimum of 20 players must register online. You can set these events to Public so that everyone can join, or Private so that only players you choose can join. The PGL support manual here provides information on how to sign up for these events.
Here is an image of a proposed Legendary tournament using rules hypothesised for VGC 2019. I wonder who the host is, not sure if I’ve heard his name somewhere…
To participate in one of these tournaments, you scan the QR code from the PGL using your DS, then select your battle team and go! More information can be found in the PGL manual.
Live events are slightly different in that you will sign up before hand, and then connect with your opponent via infrared. For those who have attended an Australian National Championship or another tournament using software, this process is similar. You go into the “Live Competitions” section of the main menu to enter. It also seems to lock the battle box of entrants just like higher level events previously have. It is yet to be seen whether this process is used for Premier Challenges and the like to prevent mid-event changes, though it definitely opens up possibilities. The event is set up online and you sign up by scanning a QR code just like you would for an online event.
QR Rental Teams
This feature allows you to borrow teams from friends to use in battle, rather than having them trade you the Pokemon you’d need to do so previously. The thrilling thing about this is that it breaks down one of the previously huge entry barriers to competitive Pokemon – having to breed and train your team. On the PGL site, you can even search for Rental teams that meet specific criteria. For example, this could be using a particular Pokemon on the team, or by a particular player. All you need to do to use a QR team is to have the code in front of you and scan it with your DS when the team selection screen comes up. See image below. You can use these teams in all manner of battles, including Battle Tree, Link Battles in Festival Plaza and most importantly Rated Battle Spot!
I sincerely hope that you all take full advantage of these new features! For full information on how to use the features on Global Link, read the manual. This link also contains information on how to connect your game to the Global Link for the first time. To access the PGL, log in with your Trainer Club account at https://3ds.pokemon-gl.com/.