I found this out on Bulbapedia and two other sites I don't remember the name of, but I now Satoshi was very young when he made the manga. I cannot find Capsule Monsters on the internet, but its very rare.
Her is the text from Bulbapedia:
The history of Pokémon spans nearly a decade from when work began officially on first game to now. It started simply enough as a hobby of Satoshi Tajiri, who as a child had a fondness for catching insects and tadpoles near his home in suburban Tokyo. Over time, Tajiri decided to put his idea of catching creatures into practice because it would give children the same thrill as he had.
With the help of Ken Sugimori and other friends, Tajiri formed Game Freak and much later the design studio known as Creatures. In 1975, the precursor to Pokémon was serialized in manga form as Capsule Monsters; however, the manga was unsuccessful and was discontinued. In 1991, Tajiri discovered the Game Boy and the Game Boy Link Cable gave him the image of insects traveling along the wire. After several failed attempts at pitching Capsule Monsters to Nintendo, Tajiri's new friend Shigeru Miyamoto pitched it to the company, and Nintendo began to fund the project, spending six years developing the games that would become a worldwide sensation. Before the first Pokémon games were released in Japan in 1996, sprites of Pikachu, Mew, Meowth, Bulbasaur, Charmander, and Squirtle appeared in Game Freak's Game Boy Camera in 1995. Around this time, Nintendo decided to change the name "Capsule Monsters" to "Pocket Monsters."
