If you're anything like me you saw this trophy and thought "you can raise the stagger damage?" Yes, you can apparently! Mostly using Tifa.
The easiest way to get this trophy is to go to Chadley and fight the Fat Chocobo VR mission. Probably best to wait until the end of chapter 14, since you'll be powerful enough that you don't need to worry about dying.
Play as Tifa. Once you're in the mission,
cast haste on Tifa - this will make things so much easier. Keep punching Fat Chocobo as Tifa until you get two full ATB bars. Use Unbridled Strength twice. Keep punching Fat Chocobo again until you have two full ATB bars again, WITHOUT using any
attacks. Also don't use any of Tifa's abilities, because you need those two ATB bars.
Your next job is to stagger him. Use your teammates' "Focused" attacks, which increase the stagger bar pretty significantly. You can do this at any time, but the best time to do it is right after he's done doing his crazy "roll around really fast and then bounce around the screen" attack, since he's vulnerable then. Once you have him staggered, do the following:
-
attack (Rise and Fall)
-
attack (Omnistrike)
- Unbridled Strength
- Unbridled Strength
-
attack (Rise and Fall)
-
attack (Omnistrike)
- Attack until you have two more ATB bars
- Unbridled Strength
- Unbridled Strength
-
attack (Rise and Fall)
-
attack (Omnistrike)
... and you should get it! I had a lot of trouble with this until I figured out I needed to cast Haste on Tifa to make her attacks go faster. Once I did that, I was able to get it on my first try.