In the Grade mode, you can play in three separate divisions to earn a ranking and qualify for rewards, which are calculated weekly.
The three divisions are: Battler in which you can only field players with three stars or less; Warrior where the restrictions is on four-star players or lower; or Champion where cards of any star rating can be used.
You must play a match to increase your ranking. You are given a choice of opponents with ranks higher than you. Defeat them, and you rise to be ranked just above them. Your ranking does not change if you lose, but given that other coaches will be leapfrogging you all the time and you only have three chances to play per division per day, you need to win to maintain your ranking let alone improve it.
Fatigue and injuries are not carried over from match to match in this mode.