ピカピカ (Pika Pika)
This sound effect is the Japanese sound for light glimmering off the surface of an object. Think of it as an audio reference to light rays hitting the human eye.
In other words, it is a human sound that represents the glimmer and glitter of light.
The waxed, bald head of a man may be said to ピカピカ (pika pika) in the light.
A waxed Ferrari ピカピカ (pika pika)’s in the sun.
A gold-colored Mobile Suit may ピカピカ (pika pika) and bring attention to itself. Clearly, a pilot of such a machine must have a great deal of confidence.
A bright flash of electricity, such as that emitted by a yellow rodent in a video game or anime, may be said to ピカピカ (pika pika) because of the light dazzles the eyes.
Thus, we may read ピカピカ (pika pika) as “dazzle, dazzle” or “glimmer, glimmer” or “sparkle, sparkle” and so forth. Regardless of the English we use to represent the sound, it is the same category of sound in actual Japanese.
Incidentally, “Pikachu” is a combination of two sound effects. The first is “pika pika.” The second is “chuu chuu,” representing the squeaky sound made by mice and other small rodents.