LogFAQs > #922017539

You should be able to get a Fire Resist Persona for her and can pass on Physical Resist from Slime I think. Orobas or Archangel are good ones to use in the fight. Orobas has Fire resist and a pretty solid physical attack if I recall and Archangel gets media I think. Once Yukiko summons her Prince you should be able to knock it down with Chies Ice attack and then have her guard with her Once More to avoid having Yukiko hit her Fire weakness. If all else fails gaining a few levels wont hurt just because youll get access to Mabufu and Magaru to do a little extra damage to Yukiko while also hitting the Prince.