The original Pokémon is a role-playing game based around building a small team of monsters to battle other monsters in a quest to become the best. Pokémon are divided into types, such as water and fire, each with different strengths. Battles between them can be likened to the simple hand game rock-paper-scissors. For example, to gain an advantage over a Pokémon that cannot beat an opponent's Charizard character because of a weakness to fire, a player might substitute a water-based Pokémon. With experience, Pokémon grow stronger, gaining new abilities. By defeating Gym Leaders and obtaining Gym Badges, trainers garner acclaim.

Pikachu, a yellow mouse, is the undisputed face of Pokémon and helped the series become a worldwide phenomenon. Pokémon inspired a cartoon series, movies, books, a toy line, sequels, spin-offs, a clothing line, and a popular trading-card game. In spite of a friendly interface and little violence, Pokémon has not been without controversy. In 1999 the parents of two nine-year-old boys sued Nintendo, stating that the Pokémon card game had caused the children to develop gambling problems and likening the trading-card craze to an illegal lottery. Religious groups that discount the theory of evolution have also targeted Pokémon for showing Pokémon evolving into new creatures.

In the Pokémon—or “Pocket Monsters”—video-game series, players were able to explore the game's fictional world by looking for wild Pokémon creatures to capture and tame. As Pokémon trainers, they readied the small monsters to compete in battle against other trainers' Pokémon. Although fighting was a key aspect of the game and the creatures could be injured, none ever died; when defeated, they merely fainted.

Japanese game designer Satoshi Tajiri created the first Pokémon game in 1996 for the recently introduced Nintendo Game Boy portable console. The concept arose from his childhood hobby of collecting insects, as well as his love of anime, or Japanese animation. Tajiri saw the Game Boy as an ideal platform because its communication cable enabled players to connect their consoles and play together. Also, the pocket-sized device allowed busy Japanese schoolchildren to play the game in the short breaks between their classes.

The Pokémon creatures became a sensation in Japan and around the world, inspiring a long string of video games and a similarly popular game played with collectable trading cards. These products were soon followed by a wide variety of merchandise and a long-running animated television series, both of which focused on the adventures of a human trainer named Satoshi (after the game's creator; known as Ash in the United States) and his champion Pokémon, Pikachu. A series of lucrative feature films began in 1998.

Despite its widespread popularity and commercial success, the Pokémon product line was not without controversy. Many parents and teachers expressed dismay that the Pokémon games and television series, which were marketed to primary school children, were inherently violent. In addition, some adults protested the implicit message that it was all right for humans to capture and enslave sentient beings (the Pokémon had free will and rudimentary language), and others thought that the fantastic nature of the creatures promoted occult (occultism) beliefs and practices. Adult fears and the cultlike allure of the Pokémon universe among children fostered a variety of satirical works by such arbiters of popular culture as Mad magazine and the television show South Park.