She'll be available after completing the Android saga.
00. Become Hercule's Apprentice
Skill: Power Blitz
This is straightforward like the other masters. Keep damaging her until her HP is lowered enough. The battle will end automatically and you'll become her student.
01. Release! Power Blitz!
Skill: Endless Shoot
You have to equip Power Blitz and use it to finish her off.
02. Ultimate Husband and Wife Team
Skill: Deadly Dance
You have to reduce the health of Android 18 or Krillin.
In Progress