The change in its appearance can make it scary. For example, if its usually cute yellow fur turns dark or if its bright red cheeks become a sinister red glow. Also, if it starts to behave in an uncharacteristic way, like making menacing noises instead of its usual cute sounds.
Shinjo Masayuki was a Japanese manga that told the story of Shinjo Masayuki, a high school student with magical abilities. After he accidentally obtained the ability to freely manipulate water, he had various encounters with various characters in school and in his daily life. The manga was released in 2009 and is still being released.
Obviously, the main characters are usually Pikachu. But sometimes, there could be other Pokémon that play important supporting roles. For instance, a Pichu could be a sidekick or a younger Pokémon that the Pikachus are protecting.
One interesting plot could be two Pikachus from different regions meeting and learning about each other's unique electric attacks. For example, one Pikachu might know a special move that the other has never seen before. They could then teach each other and become stronger together.
Love is a very common theme. Writers often explore how lee shin and shin chae kyeong fall in love, or how their love overcomes various obstacles. Another common theme is friendship, as their relationship might start as friends and then develop into something more.
Naruto would probably be really excited. He'd treat Pikachu like a new friend and teammate. He might try to learn all about Pikachu's powers and how it can help in battles. For example, he'd be eager to see Pikachu use Thunderbolt in a fight against an enemy ninja.
Lucario is also a popular choice to be paired with Pikachu in crossovers. Lucario has its own unique abilities related to sensing and combat. When combined with Pikachu's electric attacks, they can form a formidable team. The contrast between Lucario's more serious and stoic nature and Pikachu's cute and energetic personality also adds depth to the story.
Well, Naruto's chakra-based powers and Pikachu's electric powers can combine in some fanfictions. For instance, Naruto could use his Rasengan and Pikachu could add its electric charge to it, creating a super - charged attack that is more powerful than either of their individual attacks.