Welcome to LB. You can find this years tournament schedule here:
Tourney Schedule for 2025.
To enter tournaments you must be ranked. This means having 5 or more battles completed before a tournament begins.
Rankings work on the Elo rating system. If you beat someone who is ranked higher than you during the season, you will get more points for that win and in doing so, move higher up the current-active rankings. If you lose against someone lower than you, it'll do the opposite.
You're not teamed up with people of your level, you can battle anyone at any time. Send private or post an open battle for someone to take, it's up to you.