A Generation (often shortened to just “Gen”), in the Pokémon series, is a descriptive term used to denote a group of games that were all released in a similar time frame, usually with general compatibility with other games in the generation and usually released on the same system. Another strong indicator of a new generation beginning is the introduction of new Pokémon, especially starter Pokémon and a new region.
Roman numerals are often times used to refer to generations across the fandom, although standard numeric forms are also commonly used. For instance, “Generation I” refers to the first generation, or Generation 1. “Gen II” refers to the second generation, and so on. A full list of these can be found below, and individual pages detailing each generation are also available.
Generation I (Gen. 1)
This marks the first generation of Pokémon games, beginning with the release of Pocket Monsters Red and Green in Japan back in February 27, 1996 for the Nintendo Game Boy (with Super Game Boy enhancements), and releasing in North America as Pokémon Red and Blue on September 28, 1998. These games featured 151 total Pokémon.
It saw two additional main series games, although only one of which made it outside of Japan. Pokémon Yellow was released in North America in 1999 and was based more on the anime series than the other main games. Lastly, Pocket Monsters Blue was a special enhanced version of the original Pocket Monsters Red and Green, with improved sprites for all of the Pokémon (these sprites were actually used in the worldwide releases of Pokémon Red and Blue, despite the games being based on the original Red and Green), and included many changes to the encounters and available Pokémon. Pocket Monsters Blue was never released outside of Japan; Pokémon Blue’s worldwide release was based on the Japanese release of Pocket Monsters Green.
[read more about Gen 1]
Generation II (Gen. 2)
The second generation of Pokémon games began with the release of Pokémon Gold and Silver for the Game Boy Color, releasing in Japan in 1999, and then in North America and Australia in 2000, and finally Europe in 2001. These games featured a total of 251 Pokémon, adding 100 new Pokémon.
A third version in this generation, Pokémon Crystal, was released in Japan in 2000, and in North America, Europe, and Australia in 2001. This game was the first game to allow the player to play as a female Trainer instead of being forced to play as a male Trainer. It also introduced animated sprites with surprisingly detailed and lively animations, the quality of which wouldn’t be matched until Generation V a decade later.
These games could connect with Generation I games using the Time Capsule, which allow the player to trade and even battle with Generation I games, though no Generation II exclusive Pokémon or moves could be present anywhere on the Generation II player’s team.
[read more about Gen 2]
Generation III (Gen. 3)
The third generation of Pokémon games began with the release of Pokémon Ruby and Sapphire for the Game Boy Advance, releasing in Japan in 2002 and elsewhere in 2003. These games brought the total number of Pokémon up to 386 and added 135 new Pokémon. However, the ability to trade or transfer from previous generations was completely removed, so upon the release of Ruby and Sapphire, only the Hoenn region’s 202 Pokémon were available without cheating, and 2 of those Pokémon were event-exclusive (Jirachi and Deoxys).