She is Bree Davenport's alternate personality when her Commando App activates. Douglas gave her the Commando App which he calls Spikerella. She only appeared in "Spike vs. Spikette", due to her app being temporary.
Since Spike refuses to hurt Spikette, Bree says if she was Spike, she would show Spikette who's boss. Douglas says he could give Bree the Commando App, Bree refuses at first, but Douglas says it's a new version which he can shut down as soon as she's done. Bree still refuses, but after hearing that she can rip Chase apart, she agrees. So Douglas gives Bree a Commando App called Spikerella.
Spikerella then activates, and goes over to fight Spikette. When Spike says girls can't fight, Spikerella throws Spike. Spikerella and Spikette continue to fight. When Spikerella overpowers Spikette, Douglas tells her the chip extractor is almost done and to take her down, Spikerella tells Douglas to shut it or she'll take her down. Spikerella then takes down Spikette, and Douglas takes Spikette's chip out. When Spike returns back to Chase, Spikerella still think it's Spike, so she chases after him.