Final Fantasy XIII: Freaking Eidolon Battles
The Eidolon battles in Final Fantasy XIII are stupidly hard. These are the battles where you fight against a summon monster in order to gain the ability to summon it in battle.
Now you might be assuming I'm complaining about them being challenging. Except they're not, they're basically just rapidly switching between Paradigms and mashing X. (Or A on the Xbox 360.)
No, instead they're needlessly hard because of the way they're designed.
First, you're expected to lose the first time through. There's no doubt that this is the mechanic because in multiple instances you're thrown into the battle without any chance at configuring the party - the first time through. Retry, and then after skipping the cutscene you'll be given the menu.
Which is important, because you must have certain paradigms equipped. What paradigms? Well... that depends on the Eidolon you're fighting. You figure that out by casting Libra on it. Twice. The first one just tells you that you can win by damaging it, the second one tells you the other things you need to do to win.
So after the first attempt, you now know what you need to do, and you're given a chance to actually equip the right Paradigms.
You might be fooled into thinking that a guide could help you with that second part. Nope. Even if you already know ahead of time, for three of the Eidolons, you can't select the party that fights them ahead of time and therefore can only select paradigms after dying once.
Then there's the forced party. In all cases, you must use a certain party. For three of these, it makes story sense, since they're the only ones there, and you can sort of plan ahead. The other three, you're traveling with all six characters, but still are limited to a certain set of characters. In one case, despite the fact that all six characters are there, you're only allowed to use two characters. This makes that battle far more difficult than it needs to be.
The Crystarium system grants CP to all characters regardless of whether they were in the party, so you're at least guaranteed that all characters are equal power levels, right? Of course not! There's another character advancement system in the form of leveling up weapons. Each character has their own unique collection of weapons. And leveling up weapons uses up "Components" and need not be spent evenly between characters.
Which can easily leave you forced to use under-powered characters with crappy equipment because you never bothered leveling up their gear.
Oh, and did I mention these battles are timed? You have a time limit in which to complete them in. This makes the "cast Libra twice" part even more annoying because it means you're wasting time.
Fortunately you only have to deal with this crap six times, but still, it's pointlessly annoying.