Your grade gauge will increase or decrease based on your performance in races and battles.
Once this gauge has increased to a certain amount, your grade will increase. If this gauge decreases to a certain amount, your grade will decrease. The higher your position at the end of a race or battle, the more your gauge will increase; the lower your position, the more the gauge will decrease.
Notes:
・ Players subscribed to the Gold Pass will not have their grade drop below S after reaching grade S.
・ Races and Battles via With Friends or Others Nearby have no effect on your grade.
・ Please see the below for an explanation on how grade changes when your Gold Pass subscription expires.
What happens to my multiplayer grade when my Gold Pass subscription expires?