Here are my suggestions:
Avery
[name_f]Clarissa[/name_f]
[name_f]Anastasia[/name_f] ([name_u]Stacey[/name_u] or [name_f]Anna[/name_f])
[name_u]Kendall[/name_u]
[name_f]Nicolette[/name_f]
[name_f]Rachel[/name_f]
[name_u]Kelly[/name_u]
[name_f]Ashlyn[/name_f]
[name_f]Karina[/name_f]
[name_f]Veronica[/name_f]
[name_u]Sloane[/name_u]
[name_f]Angelina[/name_f]
[name_f]Jenna[/name_f]
[name_u]Ashley[/name_u]
[name_f]Elizabeth[/name_f]
[name_f]Alliyah[/name_f]
[name_f]Tamara[/name_f]
The worst girls in my school were:
McKenna
[name_f]Julia[/name_f]
[name_f]Kylie[/name_f]
[name_u]Jaden[/name_u]
[name_f]Emma[/name_f]
[name_u]Izzy[/name_u]
Some people I remember were:
[name_f]Rachel[/name_f]
[name_f]Amelia[/name_f]
[name_f]Esther[/name_f]
[name_f]Zoe[/name_f] or [name_f]Zoey[/name_f]
[name_f]Cami[/name_f]
[name_f]Isabella[/name_f]
[name_f]Tessa[/name_f]
[name_u]Alex[/name_u]
Here’s some ideas for you, I would suggest staying away from the stereotypical mean girl names like [name_f]Britney[/name_f], [name_f]Stephanie[/name_f], [name_f]Tiffany[/name_f] just because of how cliche and repetitive they can be. These are all names of mean girls from when I was going through school. (I was bullied a lot)
[name_f]Kayla[/name_f]
[name_f]Gemma[/name_f]
[name_u]Taylor[/name_u]
[name_f]Julia[/name_f]
[name_u]Julie[/name_u]
[name_u]Remi[/name_u]
[name_f]Diana[/name_f]
[name_f]Kylie[/name_f]
[name_u]Madison[/name_u]
[name_f]Abigail[/name_f]
[name_f]Georgia[/name_f]
[name_f]Jenelle[/name_f]
[name_f]Hayley[/name_f]
[name_f]Becca[/name_f]
FYI, this was posted almost eight years ago lol
The mean girl names that came to my head were:
[name_f]Ashely[/name_f]
Oakely
[name_u]Everly[/name_u]
[name_f]Birdie[/name_f]
[name_f]Heather[/name_f]
[name_f]Natalie[/name_f]
[name_f]Isabella[/name_f]
[name_f]Delilah[/name_f]
[name_f]Tiffany[/name_f]
[name_f]Krystal[/name_f]
[name_u]Sierra[/name_u]
[name_u]Piper[/name_u]
[name_f]Felicity[/name_f]
[name_f]Violet[/name_f]
[name_f]Veronica[/name_f]
[name_f]Victoria[/name_f]
[name_f]Stella[/name_f]
That [name_f]Abigail[/name_f] name is so overrated! Disgusting name! 
This is just because some people I’ve met with this name have been like the popular rude ones
[name_u]Ruby[/name_u], [name_f]Evie[/name_f], [name_u]Stacey[/name_u], [name_f]Olivia[/name_f], [name_f]Harriet[/name_f], [name_f]Lucy[/name_f], [name_f]Emma[/name_f]