If there is a argument or conflict between MG one can challenge another to a duel to resolve the issue.
“The duels are held in a special arena, and the fight is only until one’s Aura is depleted. The arena itself is heavily enchanted to detect anything that might seriously injure a Guardian, and can place a shield around anybody in danger in milliseconds. In the twenty-one years of Magical Girl duels, there hasn’t been a single death.” Naiad ch.35
“There are also various rules and regulations about who can challenge who, but that’s besides the point. The duels themselves can also be refused. No Magical Girl is obligated to accept a challenge, although refusing a challenge when somebody has a legitimate complaint can have social consequences” Ever ch.35
“one of the things that can be done in a duel is making a wager. Usually, it’s points, though only a limited amount can be gained or lost per month through duels. More importantly, there are other things that can be wagered.” Ever ch.35
“Patrol zones, for instance, if two Guardians are arguing who gets dibs on a certain location if Usurpations show up, they can wager the area in a duel. That’s probably the second most common wager, but there’s not really a limit to what can be put up for grabs.” Naiad ch.35
Of note:
Ever to Mai “You could make a wager for people to leave you alone and have it be officially enforced.” Ever ch.35