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.
Amongst units, a stand out unit in a batch usually receives this status. This is fairly relevant in terms of gameplay, since the staff often holds a popularity poll that determines which unit will get a rate up.
Thanks to its notoriety in the fandom, the Thunderbird line have reached this status, making it possibly one of the most iconic unit in the game.
For NPCs, Lugina, Seria, and especially Karl are very popular.
"Brave Burst spam" and "Critical Hit spam" team archetypes. The former is designed as such so that all of your units can use their Brave Burst every turn. The latter is designed to make full use of Mad God Zebra's Leader Skill, which increases damage from critical hits to absurd levels, by increasing the critical rates of your units as much as possible.
Units like Felneus and Uda can also do this when combined with units with high hit counts like Douglas and Serin due to their Ares' Excelsior Leader Skill (which boosts the effect of Brave Crystals) and Super Brave Burst (which increases the drop rate of said Brave Crystals).
Deemo and the Girl for Spark team archetypes, because their Leader Skill, "Charm" (4 Star) and "All Charm" (5 Star), fills a unit's Brave Burst Gauge a bit every time you hit a Spark. So with high hit count units, such as Douglas, Elza, and Serin, and Deemo as your leader, you'll most likely fill up your gauge before even getting the Brave Crystals. Not to mention that their Brave Burst, "Friction" (4 Star) and "Magnolia" (5 Star) also boosts Spark damage for all units for 3 turns. So you can potentially one shot some bosses with Deemo as your leader. Knowing that they're gonna get a Six Star in the future, one can only wonder if they're going to be even more broken than before.
Speaking of Douglas, he was a prominent example of this trope. When Douglas first got his 6* form, he went from a terrible unit with Random Brave Burst, into the first unit who had a 30 Hit Multiple Target Super Brave Burst with 30 Drop Checks. Douglas also carried a 50% buff to Spark damage on his Super Brave Burst, which, when combined with his bc production and sparking potential turned him into one of the best offensive units in the entire game by a long shot. Douglas alongside Felneus proceeded to dominate every season of Frontier Hunter, and it's said that the best team at that time for every content except for Arena was a Felneus Leader coupled with a full team of Douglas. It was bad enough that he was one of few units who got hit by a nerf (which did not work as it intended), and was a subject of balance issues until Power Creep kicked in and units such as Luther and Elza, both of which are completely superior versions of Douglas, were introduced.
Many considered the damage mitigation units to be this thanks to their ability to significantly reduce the damage you take from your opponent. The existence of damage mitigation units pretty much renders everything but the absolute hardest content in the game to be an absolute joke, at which point they become almost necessary to have a chance of winning.
Maxwell is usually considered THE best unit in the game, having amazing stats, ridiculous Brave Crystal generations, and a fairly amazing set of Brave Bursts, including her Super Brave Burst which has a ridiculous damage multiplier and hit count. Even better, Maxwell has a Leader skill that increases damage for both Critical and Elemental Weakness, on a multiplier that is fairly close to Zebra and Mare (both of which being considered units with broken Leader skills that are only being held back by their mediocre stats), practically turning it into by far, the best Leader Skill in the game. Of course, to acquire Maxwell, you need to have a squad that is strong enough to survive and beat the third Trial, which in itself is VERY difficult.
Hadaron's Super Brave Burst grants him the "Stealth" ability for two turns. If he's the only unit alive while he has Stealth active, the enemies won't be able to attack at all. With the right setup, Hadaron can use his Super Brave Burst every other turn all by himself, maintaining "Stealth" indefinitely and rendering most fights trivial. (A few bosses have passive effects that stop a solo Hadaron from filling the Super Brave Burst gauge consistently, but the notorious "Trial 003: Maxwell" is not one of them.)
Goddamned Bats: Unicorn and Pegasus have an incredibly long attack animation. The paralysis effect they carry with their normal attacks can easily bring them to Demonic Spider tier.
The Thunderbird line, despite having a great improvement of the 5-stared Zazabis stat-wise, is still labeled as the worst units and are the last one people want to receive from Rare Summon. Then again, Zazabis weren't grouped together with its lower counterparts in their receiving end of mockery.
Zazabis' 6 Star evolution, Ardas, completely reverses this by making its BB and SBB Area of Effect attacks and having a 70% Spark damage buff on its SBB.
Eric is another one due to even his Super Brave Burst hitting random enemies.
The Thunderbird line itself turns into a popular meme, commonly seen in Rare Summon jokes.
Thunder Vortex Arena.
Server Error and compensations in general has become a joke amongst the fandom.
There's now a growing trend of people claiming some of their units as their waifus.
All Hail Ding Dong Sobida! explanation Just recently, a Server Engineer named Ding Dong Sobida was added to the credits. Since then, the server suffers little to no unstability. Cue all the praising. Even better, Mr. Sobida got promoted to Server Engineer Lead soon after.
The Scrappy: Ciara and Semira were part of a notorious Halloween event that was largely considered little more than a blatant cash grab. Although there wasn't anything wrong with the units themselves, you were required to have one of them in your party in order to challenge the last level of the special Halloween dungeon - which was, of course, the one with the biggest reward. The two units could only be acquired by using the Rare Summon gate, which costs five gems and gives you a randomly selected (rare) unit. The chances of either Ciara or Semira being the randomly chosen unit was fairly low, but if you used the Rare Summon gate ten times during the event you'd be "gifted" one of them as a bonus. Gems cost $1 from the store and are given out very, very slowly during regular play; if you didn't happen to have hoarded all the gems from a few months' worth of free play, you'd have to pay up to $50 in order to get your hands on one.
To add insult to injury, when Ciara's and Semira's six-star forms became available, their Brave Burst and Super Brave Burst skills had a damage modifier much, much lower than almost every other comparable six-star unit. After a few days and much whining, this was fixed via patch.
Scrappy Mechanic: Brave Bursts that hits random targets are frowned upon for their unpredictability and are deemed unreliable. In fact, this is how some units recieved Memetic Loser status.
Ship Tease: There's a few of this in the unit's flavor text.
Zeln/Nemia: Certain on Zeln's side, considering that his 4 stars and 5 stars evolution stated that he focused on training himself to follow her.
Vargas/Lava: Small, but there. Also crossover with Foe Yay, considering that she defeated him before opening up to others, and in her 5 stars evolution it was stated that she "wanted a rematch with Vargas even more than a battle with the gods". Also, Vargas's 6 stars evolution outright stated that the wings on his back were given to him by Lava.
Loch/Edea, at least one-sided, considering he chose to come out of his self-imposed exile to join her.
That One Attack: Sir Sancus Xenon Lv10's Area of Effect attack Soul Desecretion, especially when he casts it thrice in a turn. That attack can and will most likely kill your entire squad if you're not guarding.
Dual Blade God Eru's "Necro Fusion"; Massive AoE Attack that cannot be mitigated.
Really, any of the Elgaia Heroes' AoE attacks; Especially if you kill their partner beforehand.
Trial 003 Maxwell's Endless. If a unit doesn't have 50% damage mitigation AND is not guarding, they WILL die no matter what.
Destiny and Meteor can count as well; especially if she's buffed with Sacred Song, which boosts her Attack, Defense, and gives her an ignore defense buff.
Zevalhua's Gloria, which will kill you unless you use Magress's UBB or deal enough damage within 3 turns to deactivate it.
Any time you're facing Phoenix. It constantly uses its Brave Burst, which lets it regenerates for a few turns before using it again. Unless you have poison or paralysis, it'll either be a long or impossible fight, depending on whether you can damage it more than it recovers.
Miracle Totem when you're first trying to evolve some of your units to their 6* form. Not only it can cast Brave Bursts of different elements, it also has a new move, Chaos Trilogy, that can, together with using other attacks at once even knock out 5 star units!
Thunderbird and Great Falcon Ziz due to their both their bad stats and Brave Bursts attacking random enemies instead of all. They are also flat-out scrappies as they can be randomly summoned from the Rare Summon, especial when players expect better units. Zazabis, on the other hand, gets the underrated treatment. Its stats are better than expected, so at least it's usable on boss fights that are only one enemy.
And then Zazabis' 6 Star evolution comes along, and summoners regret selling/fusing him away because his SBB is now an 27 hitArea of Effect attack and provides a 70% boost to Spark damage.
And among the ones normally obtained in-game, healing units are basically the inversion. Finkell and Legnaura are special mentions for being easier-to-obtain (though inferior) versions of Alpha Tree Altri and Phoenix Reborn, respectively.
What an Idiot: Admit it. This is your reaction to some of your units who had their chances to use their Brave Bursts in The Arena, but didn't use them, leading to the opposing team wiping you out entirely with theirs.
Viewer Gender Confusion: Official flavor texts explicitly refer to Atro as male, but there are many who would insist that "he" is actually a "her." The confusion was so bad, even the translator dubbed his 5-star name as "Goddess Atro" before the term was corrected in a recent version, and even then, it took further updates to correct all his gendered terms. His somewhat androgynous appearance certainly does not help.