These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
That One Attack: Pretty much every attack from the last boss, If playing from the remake Evolution Worlds it may appear that this trope is false but the boss was MAJORLY nerfed from the previous game. His attacks consist of: a claw that pretty much always hits critical (more or less form what I've seen), A Gatling gun that hits everyone and has an added effective of sleep, grabbing one character and throwing him back one row while dealing near death if at full health, and a large rocket that hits everyone doing intense damage. To add the cherry on top, these are pretty much ALL of his attacks.
That One Boss: Eugene, not only does he have the large array of That One Attack, he also has his own array of items which include Minalion Royal (which heals 3000 health, the strongest attack can deal somewhere in the range of 1500) and Clear Light (Which removes any status changes from your team). Both of which can be used infinitely.