Penny first appears as a cheerleading squad to celebrate the school's opening day and welcoming the freshmen.
After Will becomes popular, she eventually shows her true colors being sarcastic, rude, arrogant, and mean. She then uses her clones to keep his "Sidekick" friends from sitting with them.
During homecoming, she teams up with Royal Pain, Lash, Speed and Stitches to turn all participants into babies. She, along with Lash and Speed, later catch the six sidekicks in the hall, and chooses Layla as her opponent. Her ignorance of Layla's true power becomes her weakness when she punches her in the face. In anger, Layla defeats her and her clones by turning the cafeteria into a rain forest and immobilizing them. After this, the real girl tells her where the pacifier is. She is later seen in the detention room along with her group.
In the ending sequence, Will explains that she and her group have been sent to jail.
Penny's power is to replicate herself. Aside from replication, she is also very athletic, which serves as a trait in battle. She has enough power to create an entire cheerleading squad, which also works as a team.
Penny is portrayed by the twin actresses, Malika and Khadijah Haqq.