Armored Core

The stagger lock on your AC really only happens if you spend too much time on the ground. Try and stay in the air and use the double slash to stagger the boss faster. You need to be aggressive with the build they gave you. Hiding behind the buildings when you've run out of energy or are reloading is important too. missiles also generate a lot of stagger. Everything about this fight revolves around stagger.

This boss is less about being mechanically taxing and more about figuring out the tricks to beat it easy. I've also seen people talk about assualt boosting to get close to the boss to use the laser sword as a strat.