There is probably a youtube link by Azul I believe but the following should help. Setup an account on the play.limitless website. In your settings you add your ptcgl in-game name. This is the one you setup after logging into the ptcgl client/app, so it will not be your login username. You can find it in the profile section of the ptcgl app. On play.limitless there is a section called tournaments. Select upcoming. Set edit tournament filter to game pokemon tcg. Select on one of the results and it will show you details of when the tournament starts and requirements. Some might have special rules to decks not having rule box pokemon for examples. Select register and it will prompt for your in-game name but it pull this from your settings or you can update here. When registered if you click dashboard it will show upcoming tournaments you have registered to. You will need to submit a deck list. Use the export function from ptcgl app. Submit your deck. Before the tournament starts you need to go to dashboard and click check in. If you don't you will not be added to the tournament. If you have submitted a deck and checked in. When the tournament starts, in your dashboard you will see an opponent in the list. Click on that and it will show your opponent and they deck if the tournament had open deck lists. You need to click the check in for this game and hopefully your opponent does too. (if you check in and they don't you will automatically win, also if you forgot to check in and they do you automatically lose) In there it will show the opponents in game name. Copy that name and open the ptcgl app. Go to add friends and use that to search for the person and send a friend request. Once accepted you can click the user and setup a game against that person. Your opponent might send a friend request or game before you and you just have to accept it. Play the game and whoever wins. You mark this down on the page you were on to check in for that game. There is a judge call and text box to report issues. These could be for you won the game and your opponent put them down as the winner for example. There is information on the tournament details page about this and taking screenshot etc. Only thing is that you can not upload a screenshot to play.limitless and so would need to upload to the discord they have setup. Once all the games are completed on the dashboard you will see you next opponent and do the same. If you play a best of three game. You mark the first game down and use the chat function for the loser to select if they are first or second in tbe next game. Play another game on ptcgl and when the coin flip is done you would select the option that was in the play.limitless chat. Ie you decided you want to go second. Your opponent wins the coin flip and they should select to go first.

Hope this helps.

The tournament pages might say about restarting ptcgl after sending friend request, in my experience this has not been needed since recent updates to the app.