This Zubat, nicknamed Mimi, is a Zubat which is owned by Dr. Anna.
Anna owned a Zubat nicknamed Mimi, who used Supersonic to check patients with ultrasound. Brock was amazed and sent his Zubat, to see they both have one. When Team Rocket passed through the hallways, Anna, Brock and their Zubat followed them. Since they fall into a chamber, Mimi used Supersonic to guide them out.