Now, its not new that some Pokedex entries can get dark. I ran across Cacturnes:

"If a traveler is going through a desert in the thick of night, Cacturne will follow in a ragtag group. The Pokémon are biding their time, waiting for the traveler to tire and become incapable of moving."

That's pretty damn dark. The use of the term traveler emplies that were not not just taking Pokemon here. I was going to make a thread asking is this the darkest Pokedex entry and then this one about one of my personal gen 1 favorites Primeape pops up:

It has been known to become so angry that it dies as a result. Its face looks peaceful in death, however.

I am all for Pokemon treating Pokemon as the animals of their world. Cacturne's entry is no different than Hyena behavior;showing the more animalistic sides of Pokemon, but that is soo dark. Primeapes's anger has always been portrayed as aggressive competitive anger, but pyschological mania Rage? Theen emplying he found peace in his own death? holy shit.

Now.....any other good dark ones :)?

I remember there is this ghost who sucks your soul if you look on its back, and another one which kidnaps children, and them are never seen again.

So angry that it dies. lol

Not sure about dark ones but Mimikyu's is sad if I recall correctly.

Yanmask.

"Each of them carries a mask that used to be its face when it was human. Sometimes they look at it and cry."

SMT is dark. PKMN had a good start with blue/red. But fuxxed up with ice cream PKMN and all that round looking characters. Just for kids. Wish they would return to their old designs.

Gen 1 had a purple cumstain, an upside down pokeball, and three magnemites glued together

Get your nostalgia out of here. Red/blue are awful now. The games are terribly outdated. However, like all generations, there are hits and misses for the pokemon. A few bad ones doesn't mean the dedigns are bad now

Wow. A ballon..... I am so hyped for SMT on the switch. Maybe MH Stories will find its way also on the switch. Than i am happy. The Monsters in MH Stories are awsome. No ice cream or Balloon monsters.

All of the PKMNs in the first gen looked like dragons or crazy bad asa Monsters. Compare it to ice cream and little teddy bears. 

We get it, you don't like a select few Pokemon from various gens. That's not what this thread is about though, please stick to the topic.

OT: The sandcastle Pokemon Palossandfrom Sun and Moon has a pretty dark entry:

"Buried beneath the castle are masses of dried-up bones from those whose vitality it has drained."

or its basic form Sandygast:

"It takes control of anyone who puts a hand in its mouth. And so it adds to the accumulation of its sand-mound body."