The Worst Grade Miis page shows the Miis that have minus Grade Levels.
Some other Links:
1.) Sary | Lowest Grade = Level -★960 millinillion (6 Millon zeros)
2.) Gary | Lowest Grade = Level -★900 decillion (33 zeroes).
3.) Herta | Lowest Grade = Level -★928
4.) Velima | Lowest Grade = Level -★682
5.) Quinda | Lowest Grade = Level -★97
6.) Yasuko | Lowest Grade = -★81.3
7.) Ivy | Lowest Grade = -10
8.) Rallor | Lowest Grade = -9
9.) Fung-shong | Lowest Grade = -5
10.) Samr | Lowest Grade = -5