This page explained in detail about Chapter 15: The details of the "The Valkyrie" bosses that appear in the Sector 7 Collapsed Plate Area, as well as a battle guide.
This is put together for the difficulty level hard. There may be changes in behavior and behavior with other difficulty levels.
The battle reference video is in the middle of this page.
Wind is recommended over lightning when aiming for weaknesses (lightning may be marked "RESIST").
The administrator Arracked up the aero-type magic.
●1st Level (HP Gauge from about 100%)
・Attack with aero when it's not moving.
We can put you under pressured right away with aero.
●2nd Level (HP Gauge from about 80%)
・Firewheel
It will rotate and approach you. This rotation can do a lot of damage on Cloud's Counterstance. And we can put them in a burst.
Let's attack it all at once with an aero system.
●3rd Level (HP Gauge from about 40%)
・Pale rays of light from floating objects→Staggered Chance!
This will always chase after their friends.
This giant rays of light won't do any damage on contact. After about a second, it turns into a huge beam of light and deals massive damage to companions within range.
When this huge beam of light hits the Valkyrie, it can put you in a Pressured state.
This is your chance to defeat them, so attack them all at once with Focused Thrust and Aeroga!