Digimon: Digital Monsters (1999)

Seven kids attending a summer camp in Japan are transported to an alternate world linked to ours by the Information Superhighway. That's why it is called Digiworld. The kids make friends with strange creatures called Digimon who become stranger as they "digivolve". During the course of the story, the kids learn that they and the Digimon are the only hope of saving both Earth and Digiworld from total destruction.