For those who don't know, the girls in Madoka become Magical Girls/Puella Magi by forming a contract with Incubators. The contract is made by making a wish (nothing too outlandish, although there are some circumstances where this can be disregarded...). The Puella Magi then fight Witches because they feed on people's hopes and dreams. Upon defeating a Witch, a Grief Seed is produced, which Puella Magi can use. However, because Grief Seeds are somewhat hard to get, Puella Magi often have to fight one another and gain control of a "territory".
There is another catch: When the contract is made, the Puella Magi's soul is placed into a Soul Gem. If someone threw the Soul Gem quite a distance from the Puella Magi, they would become a motionless shell. If the Soul Gem breaks, they die. If they don't purify it with Grief Seeds picked up from Witches, they turn into Witches themselves. The Incubators claim that they turn the girls into Puella Magi and then into Witches because their emotions supply the world with energy (or something like that).
Now, here's where Pokemon comes into play: The Incubators discovered a world where strange creatures and humans work together. They sent a few spies to observe the human race, which was rather easy considering how they looked similar to the "Pokemon". Eventually, they learned about the legend of Jirachi and decided to take advantage of it by creating an Incubator that looked just like it. This Jirachi impersonator would go around forming contracts with girls
and boys, producing both Puella and Puer(? Idk this is what Google Translate gave me) Magi. However, unlike the world Madoka lives in, these Magi could only use support magic on their Pokemon, be it increased Speed, Attack, Defense, "Magic" (Special Attack), "Magic Defense" (Special Defense), Regeneration, etc.
Unfortunately for many of the original Puella/Puer Magi of this world, there was nothing to purify their Soul Gems with, and as a result the Soul Gems became impure. However, instead of turning into Witches, the Puella/Puer Magi turned into "darker" and weaker versions of the legendary Pokemon. They were visible to all, and could only be defeated by Pokemon under the command of Puella/Puer Magi.
In the case of the people participating in this RP, they would be Puella/Puer Magi who formed a contract with "Jirachi" and thus have to fight off the "Dark Legends" (as they call them). The Dark Legends would also have Familiars, these being Pokemon of similar types (e.g. Familiars of Giratina would be Gastly, Mismagius, Spiritomb, Dragonair, etc.). They can fight one another, too, and the number of Dark Legends of the same "species" is unlimited seeing how there's only a certain number of them.
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Keep in mind this isn't what the actual plot entry will look like, and I still need to figure out a region (I'm thinking of choosing all of them and creating some way for people to travel between regions quickly). For more details on the world of Madoka, the
Puella Magi Wiki is probably the best source. And if you feel it takes too long to read all the episode pages,
the site also has a funny parody in pictures!
And yes this paraody originated in 4chan.