I’ve been reading the Alolan Dex entries. Some of these are actually pretty dark, even compared to past entries:
Psyduck: As a result of headachesso fierce they cause it to cry, it sometimes uses psychokinesis without meaning to.
Golduck: It is said that the red part of its forehead grants supernatural powers to those who possess one, so it was over-hunted in the past.
Primeape: It has been known to become so angry that it dies as a result. Its face looks peaceful in death, however.
Alakazam: It is said to have an IQ of approximately 5,000. Its overflowing psychokinetic powers cause headaches to anyone nearby.
Gengar: Should you feel yourself attacked by a sudden chill, it is evidence of an approaching Gengar. There is no escaping it. Give up.
Cubone: When it thinks of its deceased mother, it weeps loudly. Mandibuzz that hear its cries will attack it from the air.
Gyarados: A tale is told of a town that angered Gyarados. Before the sun rose the next day, flames utterly consumed the town, leaving not a trace behind.
Scizor: It uses its wings to adjust its body temperature. Otherwise, its metal body would become too hot and melt in the heat of battle.
Wailord: Wailord pursue their prey in pods. With their large mouths, they can swallow entire schools of Wishiwashi whole.
Flygon: The flapping of its wings sounds something like singing. Those lured by the sound are enveloped in a sandstorm, becoming Flygon’s prey.
Glalie: Legend says a boulder on an icy mountain absorbed the distress and regrets of a stranded mountaineer, giving rise to Glalie. (A/N: Tho despite the Dex entry, I don’t think Glalie was granted a secondary-Ghost typing.)
Drifloon: Stories go that it grabs the hands of small children and drags them away to the afterlife. It dislikes heavy children. Drifblim: There was once an incident in which a man took a trip riding a Drifblim, only to go missing.
Mismagius: It appears as if from nowhere—muttering incantations, placing curses, and giving people terrifying visions.
Garchomp: It can fly at speeds rivaling jet planes. It dives into flocks of bird Pokémon and gulps the entire flock down whole.
Lumineon: With its shining light, it lures its prey close. However, the light also happens to attract ferocious fish Pokémon—its natural predators.
Vanillish: Hot days cause its body to melt. It can be restored by refreezing it, but the process leaves its body slightly warped.
Goomy: The weakest of all Dragon-type Pokémon, it’s unable to breathe if its skin dries out, so it sticks to shady places. Sligoo: It has trouble drawing a line between friends and food. It will calmly try to melt and eat even those it gets along well with.
Phantump: These Pokémon are stumps possessed by the spirits of children who died in the forest. Their cries sound like eerie screams.
Zygarde 50%: This is Zygarde’s form when it has gathered 50% of its cells. It wipes out all those who oppose it, showing not a shred of mercy.
Toxapex: Toxapex crawls along the ocean floor on its 12 legs. It leaves a trail of Corsola bits scattered in its wake.
Araquanid: It delivers headbutts with the water bubble on its head. Small Pokémon get sucked into the bubble, where they drown.
Shiinotic: Forests where Shiinotic live are treacherous to enter at night. People confused by its strange lights can never find their way home again.
Salazzle: For some reason, only females have been found. It creates a reverse harem of male Salandit that it lives with. (A/N: Ok, that’s not dark. I’m just surprised by their use of the word ‘harem’.)
Tsareena: Its long, striking legs aren’t just for show but to be used to kick with skill. In victory, it shows off by kicking the defeated, laughing boisterously.
Komala: It is born asleep, and it dies asleep. All its movements are apparently no more than the results of it tossing and turning in its dreams.
Mimikyu: Its actual appearance is unknown. A scholar who saw what was under its rag was overwhelmed by terror and died from the shock.
….Rest in peace, Meowth. Moving on.
Hakamo-o: It leaps at its prey with a courageous shout. Its scaly punches tear its opponents to shreds.
Tapu Lele: This guardian deity of Akala is guilelessly cruel. The fragrant aroma of flowers is the source of its energy.
Cosmoem: Motionless as if dead, its body is faintly warm to the touch. In the distant past, it was called the cocoon of the stars.
Nihilego: One of several mysterious Ultra Beasts. People on the street report observing those infested by it suddenly becoming violent.
(Alternate, Sun entries):
Froslass: The soul of a woman lost on a snowy mountain possessed an icicle, becoming this Pokémon. The food it most relishes is the souls of men. Sneasel: It uses its claws to poke holes in eggs so it can slurp out the insides. Breeders consider it a scourge and will drive it away or eradicate it. Sharpedo: It has a sad history. In the past, its dorsal fin was a treasured foodstuff, so this Pokémon became a victim of overfishing. Vibrava: To help make its wings grow, it dissolves quantities of prey in its digestive juices and guzzles them down every day. Drifloon: If for some reason its body bursts, its soul spills out with a screaming sound. Krookodile: After clamping down with its powerful jaws, it twists its body around to rip its prey in half. Mandibuzz: It circles in the sky, keeping a keen eye out for Pokémon in a weakened state. Its choicest food is Cubone. Goodra: This Pokémon’s mucous can dissolve anything. Toothless, it sprays mucous on its prey. Once they’re nicely dissolved, it slurps them up. Necrozma: Light is apparently the source of its energy. It has an extraordinarily vicious disposition and is constantly firing off laser beams. Raticate: Its disposition is far more violent than its looks would suggest. Don’t let your hand get too close to its face, as it could bite your hand clean off.
Gengar: It apparently wishes for a traveling companion. Since it was once human itself, it tries to create one by taking the lives of other humans.
Umbreon: With its black fur, it blends into the darkness. It bides its time, and when prey appears, this Pokémon goes for its throat, and then eats it.
Alolan Ninetales: It creates drops of ice in its coat and showers them over its enemies. Anyone who angers it will be frozen stiff in an instant.
Alolan Marowak: The bones it possesses were once its mother’s. Its mother’s regrets have become like a vengeful spirit protecting this Pokémon.
Alolan Sandslash: This Pokémon’s steel spikes are sheathed in ice. Stabs from these spikes cause deep wounds and severe frostbite as well.
It also makes you feel like a dick for Mega Evolving certain Pokemon. Some of these will also be my best guesses, sorry!
M-Alakazam: As a result of Mega Evolution, its power has been entirely converted into psychic energy, and it has lost all strength in its muscles.
M-Slowbro: All the energy from Mega Evolution poured into the Shellder on its tail, leaving Slowpoke to be swallowed whole.
M-Gengar: Gengar’s relationships are warped. It has no interest in opponents unless it perceives them as prey. M-Pinsir: The influence of Mega Evolution leaves it in a state of constant excitement. It pierces enemies with its two large horns before shredding them. M-Gyarados: Mega Evolution also affects its brain, leaving no other function except its destructive instinct to burn everything to cinders. (S):When it Mega Evolves, it becomes more vicious than ever before. Some say that’s because its excess of power is causing it pain.
M-Scizor: The excess energy that bathes this Pokémon keeps it in constant danger of overflow. It can’t sustain a battle over long periods of time. (S:) Due to the effects of Mega Evolution, its pincers have taken on a more diabolical form, ripping anything they pinch to shreds.
M-Glalie: The excess energy from Mega Evolution spilled over from its mouth, breaking its jaw. It spews endless blizzards. (S): It envelops prey in its mouth, freezing them instantly. But its jaw is dislocated, so it’s unable to eat them.
M-Salamence: Anyone standing in its path gets sliced right in two, while this Pokémon continues its flight without interruption. (S): Mega Evolution fuels its brutality, and it may even turn on the Trainer who raised it. It’s been dubbed “the blood-soaked crescent.”
M-Kangaskhan: Thanks to Mega Evolution, its child grows. But as the child is good only at fighting and nothing else, its mother feels uneasy about its future. M-Metagross: Mega Evolution stimulated its brain. It emerged as a ruthless Pokémon that will clutch at any means of ensuring its victories.
M-Garchomp: Its vaunted wings become scythes, sending it mad with rage. It swings its scythes wildly and slices the ground to pieces. Even Mega Lucario isn’t immune: It readies itself to face its enemies by focusing its mental energies. Its fighting style can be summed up in a single word: heartless.
Zygarde 10%: Its sharp fangs make short work of finishing off its enemies, but it’s unable to maintain this body indefinitely. After a period of time, it falls apart.
The sarcastic fringehead is a small but ferocious fish which has a large mouth and aggressive territorial behavior. When two fringeheads have a territorial battle, they wrestle by pressing their distended mouths against each other, as if they were kissing. This allows them to determine which is the larger fish, which establishes dominance
The Sarcastic fringehead is a ferocious fish which has a large mouth and aggressive territorial behaviour from which it has been given its common name.When two fringeheads have a territorial battle, they wrestle by pressing their distended mouths against each other, as if they were kissing. This allows them to determine which is the larger fish, which establishes dominance. They are found in the Pacific, off the coast of North America, from San Francisco, California, to central Baja California. Fringeheads are ambush predators, jumping out from their shelter to surprise prey swimming or moving by.
The sarcastic fringehead, Neoclinus blanchardi, is a small but ferocious fish which has a large mouth and aggressive territorial behavior, for which it has been given its common name. Found in the pacific. source