Though present throughout the franchise, the Pokédex is often overlooked by players of the Pokémon series. You get the Pokédex when you start the game, entries are added with each new Pokémon, and you never pay it any mind. Who, after all, has time to read Pokédex entries when you can just go off and enslave animals inside tiny balls? Or beat gym leaders? Or climb up a snowy mountain to confront your character in the prior game?
However, there is a treasure trove of interesting lore contained within the Pokédex entries. Lore unlike any you'd expect from a series that brought you jumping joyful Jigglypuffs or ever-ad0rable Eevees. Indeed, some Pokédex entries are downright depressing, leaving you with a pit in your stomach that sucks away any potential joy you may ever experience in your life.
There are several Pokédex entries that demonstrate how Pokémon can be a burden to their trainers. Several Pokédex entries show how Pokémon can eat their trainers, feast upon their dreams, and steal their souls, but only Beware's presents a scenario where Beware simply loves its trainer too hard, and destroys that which it loves most.
"This Pokémon has the habit of hugging its companions. Many Trainers have left this world after their spines were squashed by its hug." - Pokémon Moon
Muk isn't a particularly lovable Pokémon. As a disgusting pile of slime, it sprouts from pollution, as almost a real-world reminder to the world to clean things up. However, in the Alola Region, Muk has an extra-special level of sympathy for this disgusting slime in its Pokédex entry.
"After recent environmental improvements, this Pokémon is now hardly seen at all. People speculate that it may go extinct at some point." - Pokémon Moon
"Their food sources have decreased, and their numbers have declined sharply. Sludge ponds are being built to prevent their extinction." - Pokémon Ultra Sun
Nosepass is probably no one's favorite Pokémon. When you combine the weird metal/rock aesthetic with that huge nose of his, many players just write it off as an oddity in the Pokémon world. However, many trainers, if they decide to catch Nosepass, are "treated" to this incredibly depressing Pokédex entry.
"Nosepass's magnetic nose is always pointed to the north. If two of these Pokémon meet, they cannot turn their faces to each other when they are close because their magnetic noses repel one another." - Pokémon Ruby
As demonstrated with Muk, multiple Pokédex entries demonstrate how Pokémon are being poached to the point of extinction. Lapras, as a whale-like Pokémon, has the real-world correlation and connection with real-life poaching, arguably making its Pokédex entries far more disturbing.
"A Pokémon that has been overhunted almost to extinction. It can ferry people across the water." - Pokémon Red and Blue
"People have driven Lapras almost to the point of extinction. In the evenings, this Pokémon is said to sing plaintively as it seeks what few others of its kind still remain." - Pokémon Ruby and Sapphire
If this story has a happy ending, recent games have included this entry:
"These Pokémon were once near extinction due to poaching. Following protective regulations, there is now an overabundance of them." - Pokémon Moon
Ghost Pokémon tend to be among the most depressing and tragic. They often represent that which we have lost in ways that are potentially incredibly disturbing. However, there is an extra layer of melancholy one feels when reading Phantump's entries -- in part because we realize they were once human.
"These Pokémon are stumps possessed by the spirits of children who died in the forest. Their cries sound like eerie screams." - Pokémon Sun
"By imitating the voice of a child, it causes people to get hopelessly lost deep in the forest. It's trying to make friends with them." - Pokémon Ultra Sun
Like Phantump, Yamask is another Ghost Pokémon with a tragic, human-based origin story. And, like Phantump, it too cries and cries. While its later evolutions have been known to turn people into mummies so it can finally have company, Yamask's is far more simple and makes it clear why an evolved version of Yamask would feel motivated to rob humans of life.
"Each of them carries a mask that used to be its face when it was human. Sometimes they look at it and cry." - Pokémon Black
"These Pokémon arose from the spirits of people interred in graves in past ages. Each retains memories of its former life." - Pokémon White
Upon release, Mimikyu was seen as an oddity. It's a Pokémon pretending to be a Pikachu. Pretending to be a lovable icon. However, upon reading Mimikyu's disturbing and depressing Pokédex entries, it's clear that this is Mimikyu begging people to love them.
"A lonely Pokémon, it conceals its... appearance beneath an old rag so it can get closer to people and other Pokémon." - Pokémon Moon
"It stands in front of a mirror, trying to fix its broken neck as if its life depended on it. It has a hard time getting it right, so it's crying inside." - Pokémon Ultra Sun
Spoink is relatively infamous for being cursed with a heart-wrenching anatomy problem. Most players look at Spoink, and see an odd pig-spring thing. If they ever chose to read Spoink's Pokédex entry, however, they'd find that this adorable little munchkin lives a hair's space away from death at every moment.
"Spoink bounces around on its tail. The shock of its bouncing makes its heart pump. As a result, this Pokémon cannot afford to stop bouncing - if it stops, its heart will stop." - Pokémon Ruby
Abandoned toys and possessions are often something we view through a depressing lens. When someone is rejected and cast away, there is a sense of sadness that we feel. But what if the pain of abandonment was so potent, it spawned a Pokémon? According to its Pokédex entry, Banette has suffered rejection so awful that it was born from pain.
"An abandoned plush doll became this Pokémon. They are said to live in garbage dumps and wander about in search of the children that threw them away." - Pokémon Emerald
"Resentment at being cast off made it spring into being. Some say that treating it well will satisfy it, and it will once more become a stuffed toy." - Pokémon Ultra Moon
Cubone's Pokédex entry is arguably one of the most infamous. This little guy has several disturbing Pokédex entries throughout the game reinforcing why it is referred to as the "Lonely Pokémon."
"Wears the skull of its deceased mother. Its cries echo inside the skull and come out as a sad melody." - Pokémon Yellow
"Cubone pines for the mother it will never see again. Seeing a likeness of its mother in the full moon, it cries. The stains on the skull the Pokémon wears are made by the tears it sheds." - Pokémon Ruby and Sapphire
"At night, it weeps loudly for its dead mother, but those cries only attract its natural enemy—Mandibuzz." - Pokémon Ultra Sun
"It wears its mother's skull on its head, so no one knows what its bare face looks like. However, it's clear that it's always crying." - Pokémon Ultra Moon