A Pikachu is the most infamous Pokemon of all, where their only goal was to destroy everything and one even gave hundreds of seizures, however, the most evil of all Pikachus is Ash's Pikachu. It doesn't evolve from the somewhat similar Pichu, and they don't evolve into the familiar looking Raichu. They always carry a gun in their back pocket (AKA their arses). They also like to kill little kids, and eat them with mustard and chili sauce. They are mutant rats that can spit cheese. It turns out they are advance blobs of cheese that are shaped to look like mutated rats. For some reason they can generate electricity using red fur (Usually thought to be blood stains) on their faces.
In the year 1778, Doctor Tree name did his first experiment which created Pikachus in an experiment where he fused moldy Cheese with Cupcakes and a thing with high voltage. After a sudden black out Pikachus were created, but they caused pain and other evil things in the Pokemon World... Just like the rest of his experiments.