Generation I

Generation I (sometimes referred to as the Color Generation due to the names of the versions released) was the very first set of games introduced in the Pokémon franchise. The games begin Pokémon Red and Pokémon Green in Japan, which are later joined with a third version Pokémon Blue and a special edition Pokémon Yellow. They were released on the Game Boy while Pokémon Stadium for the Nintendo 64 in Japan. These games featured the 151 Pokémon starting with Bulbasaur. Chronologically, these games take place during the time period of the Generation III games. These games are also all located in the Kanto region.

Gameplay
The gameplay primarily consists of the player trying to obtain all 151 Pokémon, defeating all the Gym Leaders, the Elite Four, and the Pokémon Champion while encountering other Pokémon Trainers along the way.

To find and catch a Pokémon, the player, who is a Pokémon Trainer, walks around in tall grass (or caves or uses the Hidden Move surf on water). When a wild Pokémon appears, the player battles it with a previously caught Pokemon to lower its health. Lowering the Pokémon's health weakens it, allowing the Trainer to capture it with a Poké Ball. The player is limited to carrying only six Pokémon at a time. Once the player catches a seventh Pokémon, it automatically transfers to a Pokémon storage system. Players can change the six Pokemon in their lineup by accessing the Pokémon storage system, which contains 12 "boxes" that each hold 20 Pokémon.

Each Pokémon has its own stats, which consist of Attack, Defense, Speed, Special, and HP. These stats increase when the Pokémon gains a level. The lowest level a Pokémon can be is level 1, while the highest is level 100. Pokémon also have moves, which can be used to attack another Pokémon or to heal oneself. In total, there are 165 moves in Generation I, though a Pokémon can only have four moves and will have to forget a move to learn a new one.

Pokémon also come in different elemental types. There are 15 different elemental types of Pokémon, consisting of Bug, Dragon, Electric, Fighting, Fire, Flying, Ghost, Grass, Ground, Ice, Normal, Poison, Psychic, Rock, and Water. Each element has its own weakness, such as Fire Pokémon being weak against Water Pokémon, as well as its own strength, such as Water Pokémon being strong against Fire Pokémon. Pokémon receive less damage from and deal more damage to elements they are strong against, while on the other hand dealing less damage to and taking more damage from elements they are weak against. Elemental strengths and weaknesses encourage the player to keep a diverse selection of Pokémon to counter various types of enemy Pokémon effectively.

Some Pokémon can evolve into another Pokémon. This can happen when they reach a certain level, are traded with another character or player, or are given an evolutionary stone. When a Pokémon evolves, they develop better stats and may also change types.

The player must travel across Kanto and defeat the eight Gym Leaders at their Gyms, earning a Badge corresponding with that Gym. Each Gym specializes in a type of Pokémon, resulting in certain types of Pokémon being effective in certain gyms, while other types of Pokémon are weak in certain gyms. After defeating the eight Gym Leaders, the player progresses to the Elite Four, where he/she fights the four best trainers in the entire region. After defeating them, the player must then defeat the Pokémon Champion, which will result in the player becoming the new Pokémon Champion.

Players can also trade Pokémon with or fight against other players through a Game Link Cable. Some Pokémon have to be traded so that they can evolve.

Starter Pokémon
The player can choose one of three Starter Pokémon at the beginning of the game. The choices are: Bulbasaur (Grass), Squirtle (Water), and Charmander (Fire)

However, in Pokémon Yellow, the player had only Pikachu to choose as a starter, while the rival always chooses Eevee, which evolves into either Vaporeon, Jolteon or Flareon depending on the results in the battles with him at Prof. Oak's lab and at route 22.

Gym Leaders and the Elite Four
Generation I introduced a unique set of Gym Leaders and the Elite Four. All of these trainers specialized in a specific type of Pokémon and are key to progressing through the game. They all reappear in Generation II's Pokémon Gold, Silver and Crystal, Generation III's Pokémon FireRed and LeafGreen and Generation IV's Pokémon HeartGold and SoulSilver, except for Koga, who is replaced by Janine, and Giovanni, who is replaced by Blue in Gold, Silver, Crystal, HeartGold, and SoulSilver.

Pokémon Champion
The Pokémon Champion in Generation I is Blue, the player's rival.

Trivia

 * Pokémon Green wasn't released internationally and was only released in Japan.
 * If you play any of the games on the GBC, the stars on the Game Freak logo will be colored depending on the version of the game.
 * Dragonite's horn wasn't added until Generation II
 * Generation I has the least number of legendaries.
 * It is also the only Generation to have originally introduced Legendary Pokemon with each one having unique base stat totals: Articuno had 485, Zapdos had 490, Moltres had 495, Mew had 500, and Mewtwo had 590
 * Generation I is the only Generation not to introduce a dual Water/Ground type Pokémon, as well the only Generation not to have a female player character.
 * It was originally intended that the player could battle Professor Oak after beating the champion, but it was not included in the actual games. There is however, a glitch that can be activated to battle him.

Primera generación