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.
YMMV: Final Fantasy II
Anticlimax Boss: Borghen, the foul arch-traitor who assisted the Empire in taking the heroes' hometown and thereby resulting in the deaths of their parents, turns out to be the weakest boss in the game by a mile. Moreover, after his death he sets off a trap that causes the death of Josef, meaning that this wimp also gets the honor of being the first Final Fantasy bad guy to kill off a playable character. The Emperor also fits this trope when you fight him in the Cyclone, where he's a pushover (though he turns into a killing machine for his turn as the final boss.)
Awesome Music: The ending theme, "Finale," is one of the most tender and moving for any Final Fantasy title. It was also released as a vocal version titled "Love Will Grow."
Big Lipped Alligator Moment: The giant beavers at the bottom of the Ice Cavern. Aside from giving a chance to helpfully inform us that "Guy speak beaver," they have absolutely no relevance to the plot or to anything else in the game. The most logical conclusion as to their inclusion in the game is that they were intended to be expies of Ewoks, in that their demonstratively minor actions ultimately lead to the defeat of a global empire. Likewise, Guy "speaking beaver" is probably supposed to reinforce an analogous connection to Chewbacca.
A few creatures fit this description, but Chaos Riders from Soul of Rebirth are the worst example. Insanely high defence and magic defence (you'll be lucky to inflict any damage at all); maxed out spells like Confuse, Slow and, worst of all, Osmosenote Unlike the other spells, Osmose never misses and it always drains 120-150 MP, no matter how much Level Grinding you've done; a tendency to attack in groups and a powerful draining physical attack if it were to run out of MP.
Anything that can inflict Confusion. They usually target everyone, cast it almost every round, and unlike in later games, your characters don't snap out of it upon being hit. Your confused characters will never target the enemies and take quite a few rounds to return to normal, and late in the game you're often doing so much damage that your characters can kill themselves in a matter of seconds, meaning that navigating certain dungeons is a matter of whether or not you get ambushed by these things. (The Mysidian Tower is the worst, having two enemies that can do this- Mini-Satana and Devil's Bloom.)
Cockatrices make their glorious return from the original Final Fantasy I. They still inflict stone, which is still an effective instant-kill. They do this on contact. And come in packs of 6. Your party size is only 4.
Sorcerors and Wizards that first appear in the Coliseum halfway through the game. You have a 3/64 chance of running into them (along with Captains and Sergeants, which are hard on their own), and they love party-wide status and damage spells, such as Curse, Toad, Stop, Confuse, Break, Warp, Death, Osmose, Drain, and Flare (most of which they drop as tomes upon defeat). Sorcerors can also cast Haste on the Captains and Sergeants to kill you, and Wizards have high HP and defense. If you didn't get the Ribbon from the Lamia Queen, you're as good as dead.
The Hill Gigas in the Deist Cavern hits as hard as the Captain, if not harder, and has tons of HP compared to other enemies in the dungeon, and can appear in groups of two. If you can't run or inflict Curse on them, they will crush your entire party.
Ensemble Darkhorse: Until Dissidia, odds are the only things casual fans of the series remembered about this game was Minwu. The developers took notice and turned him into a Breakout Character in the remakes, making him the focus on a secondary storyline unlocked after the game that takes place in the afterlife.
Esoteric Happy Ending: The ending warmly states that the wounds of the war would heal in time..., largely ignoring the difficulty of recovering from the utter destruction of roughly half of the world's population centers.
It's arguably more of a Bittersweet Ending in tone, especially considering Leon's departure.
Game Breaker: Buff spells, blood swords (which do damage proportional to the target's maximum HP as a result of being HP-drainers, making them deadly against bosses but mostly useless against normal enemies, and worse than useless against undead), the minigame exploit (the puzzles repeat every 32 tries, allowing for easy late game equipment) plus the leveling related issues, something that could fill most of an FF subpage on gamebreakers.
The bare fist "weapon" skill upgrades the basic damage a character does barehanded to compensate for no purchaseable weapon upgrades in this category. It ends up making fists drastically overpowered quite early in the game (by way of comparison, an unarmed character with the maximum of 16 ranks in the 'barehanded' skill has about the same attack power as a character using an Infinity+1 Sword with 16 in the corresponding skill).
A secret minigame accessible in the Snowfields allows you to play a 16 card match-type game where you receive rewards based on how fast you match all cards and how many misses you get. With good memory and fast reflexes, you can score Ethers, Hi-Potions, Phoenix Downs and thousands of gil. Did we mention this game costs you nothing but time and can be played infinitely? What about the fact that each time you access the minigame, there are only 32 puzzles "solutions" the game will cycle through, in-order? Finally, getting the Toad spell up to Level 16 increases the Gil obtained, and changes the items won from restorative items to items that cast spells and incredibly powerful equipment.
The Teleport spell. In battle, it can kill enemies instantly, and at a high enough level, you can consistently get kills against many enemies. Even better, you can level it up outside of battle by entering a town/dungeon, casting Teleport, re-entering the town/dungeon, etc. The only downside is that it leaves the caster with low HP, but you can use Cure on him/her (which, in turn, allows that spell to level up as well).
The ultimate weapons in the 20th Anniversary version give huge stat boosts, +99 for some of them, and of course have high attack power. The really game breaking ones are the ones that boost Stamina or Magic. The game's mechanics for HP and MP gain specifically increase them by the character's Stamina and Magic. So with 99 Magic and Stamina, the character will get 99 HP or MP the next time the stat levels up. Enjoying being able to smash into the MP cap in a few battles and pumping up your characters at least a thousand HP in that same time.
The Wild Rose, the ultimate weapon for Scott in Soul of Rebirth. It maxes out (among other stats) Scott's Intelligence when equipped and casts Berserk XVI when used as an item, buffing your party's physical attack power to ridiculous levels.
Good Bad Bug: In the original and PS1 versions, if one selects a move and then cancels it, the game treated it as if you had performed the move, for the purposes of raising stats. Thus it is possible to get astronomically high strength and magic skills almost as soon as you start the game, if your fingers can take it.
When facing single foes if you set a damage spell to multi target you do 1.5 times as much damage (The formula for the damage is the normal damage plus 50% divided by the number of foes).
Magnificent Bastard: The Emperor, who may have the honor of being the most relentless villain in the entire Final Fantasy series. First off, the game begins with the guy unleashing the powers of Hell upon the world and conquering a prominent kingdom. Then, he constructs a warship which bombs nearly every town in the game, kidnaps the female leader of La Résistance, replaces her with a monster and allows the heroes to "rescue" her (who then kills off the King), builds a flying castle that completley ruins nearly every town in the game, and then after being killed by the party, he takes over Hell AND Heaven and comes back stronger than before. (Whether this was on purposeor not is not clear.) This guy was NOT messing around.
The Emperor's weird death cry in the Japanese version: "UBOAR!" (And to a lesser extent, the English version "UNGAAHH!") Tidus lampshades it in Dissidia: Final Fantasy, as seen here.
Firion's scene with Hilda (well, actually a Lamia Queen) is popular in Japan as well. His reaction to Hilda's seduction ('Gulp...') has led to him being called 'doutei' or 'virgin' (which rhymes with the Emperor's title, 'koutei').
Guy speak beaver.
Never Live It Down: While the unorthodox level system has been refined by remakes, to this day this is the Final Fantasy game known for being the one where you level up by having your party members attack themselves. Unfortunately for the game, this is a perfectly viable strategy too — the best way to level up skills and spells is to cast them over and over, and your party members are likely much more durable than enemies, sooo...
Newer Than They Think/Older Than They Think: This game was the origin of a lot of Final Fantasy standbys. Newer Than They Think is for elements like Cid (unless you count Cid of the Lufaine), chocobos, etc., which weren't in Final Fantasy I—this comes as a surprise to a lot of people. And Older Than They Think comes into play with many of the plot elements—the Evil Empire, Bishounen villain who's seeking godhood, essentially, party members being Killed Off for Real, and even the presence of any plot at all—which many people seem to think only started in the SNES and PS1 era.
Player Punch: The towns you visit visibly go through the wringer over the course of the game, thanks to imperial troops and bombarding airships. After the Cyclone, however, they are gone: just a patch of ruins on the overworld that you can't enter. After being able to visit these places and see their trials for the whole game to that point, knowing that they've been wiped off the map with no survivors... ouch.