In the NES version, she follows a pattern of Tornado, Reflect, Tornado, and Snowstorm, making her a bit easier to deal with than Doga. Physical attacks are the way to go in defeating her. Using a Dragoon's Jump ability ends the battle fairly quickly. Like Doga, she is basically a pushover, though the fact that the party must fight her immediately after Doga can make her a challenge, especially if they are underleveled.
In the 3D remake, Unei is a bit more difficult, as she can inflict heavy damage with a physical attack, followed by the powerful Aeroga spell on one or all party members. She also has access to both Protect and Haste, making her faster and taking less damage from physical attacks. However, she is still relatively easy to defeat.
It is possible to obtain the Earth Crystal jobs before fighting Unei or Doga, simply by traveling to the Earth Crystal and fighting the boss there after the party obtains the Fang of Earth. Doing so almost entirely negates the difficulty of the battle.