Although Doctor Gero had lost control of Android 18 years ago, she was still his Android. Android even though she betraded the Doctor, married his enemy's best friend Krillin, and had a daughter with him named Maron, was still the doctor's creation. And the doctor still knew all her strengths and weaknesses, because he designed her. Even, a dimension away in hell, Dr. Gero could still access earth through his creation, Android 18. "Vegeta, there's this guy I really want to fight! He's right over there!" said Goku as he pointed to a dark-skin skinny boy.