Leagues are weekly rankings that can give you increased coins for all the matches you play.
When you begin your Sky Warriors adventure, you'll be assigned to a League. All new players will begin in Bronze 5. The higher your league, the more coins you'll earn in battle.
From the image below, this player is in Bronze 1 and earns a minimum of 3000 coins per win considering the League bonus.
How do leagues work?
Players are split into Leagues consisting of 3 tier divisions - Gold, Silver and Bronze - and each of those tiers is broken into 5 leagues with "5" being the lowest, and "1" being the highest. Depending on your scores during a calendar week, you can go up as well as go down divisions. You can only go up or down 1 league per week, regardless of your scores and you do not earn rewards for being promoted/demoted each week.
Your current League is shown on the home screen with a timer that indicates the next time the league's divisions will be updated. In terms of the league points themselves, these update every 20 minutes or so.
How do I access my league?
To access your leagues and see your progress during the calendar week, tap the "chart" icon next to your fuel.