Like Pokémon, Telefang comes in two versions: Power and Speed. Storywise, the game has more similarities with Digimon: the creatures, the "Denjuu", are denizens of an electronic world accessible via a cell phone known as a D-Shot. In the year 2020, the game's protagonist, Shigeki, is accidentally transported into Denjuu World. He decides to make the most of this, by befriending Denjuu and traveling the world.
The games are known best in the US and Europe for the bootlegged Broken English translations released, known as Pokémon: Diamond Version and Pokémon: Jade Version. No actual Pokémon appear in these games, and the only change other than the language to game itself are the title screens. The game notably found its way into actual game retail franchise shops such as FuncoLand.
Another well-known bootleg is a Chinese NES port known as 寵物 - 翡翠版 (Chongwu - Fei Cui Ban) . This version gives all of the Denjuu Pokémon names, and adds several actual Pokémon to the game, although none of them are named correctly.