This is Candy, she is a Shiny Lopunny.

Candy has been with Team Rocket since she was a young Buneary. Team Rocket found that she seemed to be born with the move Shadow Ball and have helped her develop her Shadow Ball technique. Candy can now control it with her paws to change its direction or she can clap her paws toghter which causes the Shadow Ball to detonate. She is kinda spoilt, as she was given more or less everything she wanted and she feels like she's the sexiest pokemon in Team Rocket.

In the scenario that Lex joins Team Rocket, she is assigned to be he training and mission partner.