Nier Automata how to beat Seventh Boss Goliath Spider On very Hard

You really want to use a yorha corpse here deal the much damage as you can during its ball form.

Mainly, best strategy imo is to keep its stun phase to a later timing, you get it stunned by hitting its tail ball enough times, if you wait with this and do it when it has low health just before it goes into ball mode, you can get it stunned over most if not all of the ball mode.