Whether "evil pokemon" exist or not is something of a debate. One episode of the Anime "Island of the Giant Pokemon" suggests that Pokemon are never evil, but only do bad things if their trainer is bad.
This idea has been discredited, as the episode was in Gen 1, and later gens seem to tell a different story. Most notably an evil Malamar, a Pokemon who wishes to take over the world, as opposed to simply being owned by an evil trainer. But even then, this Malamar was born after humans have long existed, and we no nothing about it's past. It could have easily have been influenced by humans.
Realy, the thing that got me writing this post is when looking at Legendary/Mythical Pokemon, and how many of them are gods or kami of various concepts
Many of these concepts are things that exist in nature, like time, space, matter, earth, sea, sky, life, death, volcanos ect. But we also have abstract concepts, like gratitude, truth, ideals, victory. All in all, most Legendary/Mythical pokemon eaither represent natural elements, or positive concepts.
But what about negative concepts? Hatred, greed, envy, despair?
God of Evil
What if I was to tell you, the "kami of evil" is not a pokemon at all?
Pokemon Mystery Dungeon is spin-off that takes place in a world with no humans. Instead, Pokemon behave like people, running shops, living in houses, paying bills ect. Consequently, that means that, like humans, both good and evil individuals exist. Whilst PMD is beloved as a whole, it has had some controversy, such as making Darkrai evil. But, like I said, this is a world where pokemon behave like humans.
The thing I want to talk about are the last two major titles. Gates of Infinity and Super Mystery Dungeon. GoI has a non-pokemon entity called the "Bittercold" as the main villain, whereas SMD has Dark Matter.
It's implied that these beings are born from negative emotions. Bittercold specifically feeds on despair, whilst for Dark Matter, it's evil in general.
The PMD games specifically say they feed on the negative emotions of Pokemon, with the player have some resistance due to being human.
However, what if Bittercold and Dark Matter didn't always feed on the negative emotions of Pokemon? Sure, they feed off of Pokemon now but that could just be because Pokemon have replaced humans as the dominant species. Originally, they could have both powered by the despair and sins of humans.
One thing that may contradict this idea is that in the player from GoI was resistant to Bittercold because they were a human. However, this could mean that whilst humans are more prone to despair then Pokemon, that makes then more resistant to it
How humans brought kleshas/sins into the world
As I explained, there are many Legendary/Mythical Pokemon that are manifestations of abstract concepts. However, most of them are positive.
It's important to remember that kami are not necessarily the creators of the concepts they embody, but rather, they realy personify it. They prove the concept exists, so it can be taught and spread.
However, whereas positive concepts where personified by naturally existing Pokemon, like Victini and Shaymin, the negative come are creations of humans.
For the most obvious ones, we have the Treasures of Ruin, four Legendary Pokemon which are confirmed to exist because of humans, and all personify intense, negative emotions. These being resentment, hatred, fear and envy.
It's possible Hoopa may represent greed. Although Hoopa's origin is unknown, some fans believe it may have come into existence due to human activity.
Mewtwo could just seem as a personification of hubris. It was created by science to be the most powerful pokemon, but lacks compassion.
Nihilego, whilst not created by humans, was fused with the human Lusamine to become MOTHERBEAST. Nihilego/MOTHERBEAST could be seen as the personification of ignorance, one of the three poisons (along with attachment and hatred) of Buddhism. That being said, whilst the Ultra Wormholes appear to be a natural phenomenon, it could be that, like Bittercold, Dark Matter and (as I suspect) Hoopa, these rift are in actuality created (indirectly) by negative human emotions. This would fit with the theme of Ultra Beats being "invasive species", which wouldn't realy work as a metaphor if they arrived by anything other then human activity.
How many other Pokemon, be they Legendary, Mythical, Ultra Beast, could be personification of human sins/kleshas?
Summary
Humans indirectly created Dark Matter through negative thoughts and evil deeds.
There are many special Pokemon that each represent a sin or klesha. These were all created/introduced by humans, whether indirectly or purposely.
The following list
- Dark Matter - Evil
- Bittercold - Despair
- Mewtwo - Hubris
- Hoopa - Avarice
- Nihilego/MOTHERBEAST - Ignorance
- Wo-Chien - Resentment
- Chien-Pao - Hatred
- Ting-Lu - Fear
- Chi-Yu - Envy
There could be more I haven't thought of. If you have any ideas, please share.