Throughout the Pokémon game series, each game featured its own unique features that were exclusive to that specific Pokémon game. As the game franchise progressed over time, the newer games started to utilize features from a number of the previous games. Below is a list of changes in features throughout the franchise:
Red, Blue, and Green Version
Being the first games of the franchise, Pokémon Red, Blue, and Green mainly established the games basic gameplay such as training, trading, names, etc. The only features that made Red, Blue, and Green unique was that they only utilized a single color scheme(Red being red, Blue being blue, etc). Every location, scene, and character had their own design but used the same colors and shading depending which game it was. The only things that made locations in the games unique were the music and obstacle layouts. The length of the game was limited to a single region of Japan being, Kanto.
Yellow Pikachu Edition
Pokemon Yellow version(also known the Pikachu Edition) was one of the more popular and recognizable Pokémon games in the franchises development because it was the first game to utilize detailed color schemes and character designs. Rather than using a single color scheme for the entire game, every character and Pokémon in the game was carefully designed and colored based on their designs in the manga and anime. The locations of the game as well as the region of the game remained the same as the previous games. However, each area and town used its own unique color scheme to distinguish themselves from the others. Yellow version was also the first and only game to utilize the ability to have one of the players six Pokémon follow behind him. However, it was exclusive to your assigned starting Pokémon which was Pikachu. This feature was discontinued until the re-release of Gold and Silver.
Gold and Silver Version
Pokémon Gold and Silver underwent the largest number of changes(some of which were exclusive to them). Gold and Silver were the first and only games in which everything had its own color and design which eliminated the single color scheme location concept. Gold and Silver were the first and only games until the re-release to feature the ability to change the time of the game which would after the games time of day(night or day). They were also the first games to feature Pokémon genders and Eggs. As well as a variety of new Pokémon and the ability to trade them with the older games. The game also featured new starting Pokémon and the ability to traverse from the new region, Johto, to the region from the previous games being Kanto. The game also utilized the ability to contact and rematch previous opponents and the ability to carry a radio and cell phone.
Pokémon Crystal utilized all of Gold and Silvers features but was the first game to utilize Pokémon animations in which summoned Pokémon performed brief moving animations during battle sequences. The feature was not reused until Emerald and the versions that followed it.
Ruby and Sapphire Version
Pokémon Ruby and Sapphire were the first Pokémon games to utilize weather changes. They were also the first games to utilize 2-on-2 Pokémon battles in which both trainers could summon two Pokémon at a time rather than the traditional 1-on-1 layout. The game also featured the ability to build customizable camps or "secret bases" in various locations of the playable region that served as makeshift homes for the player. The only features to carry on from the previous games were genders, eggs, and further graphic improvements.
FireRed and LeafGreen Version
Pokémon FireRed and LeafGreen were among GameFreaks first attempts to utilize several of the previously unique features exclusive to the past games. Fire Red served as the spiritual successor of the original Pokémon Red and Leaf Green served as the spiritual successor to the original Green version(which was unique on its own since Green was exclusive to Japan). The original Blue version did not receive a spiritual successor due to GameFreak's belief that Green version was practically unnoticed in the franchise and thought it deserved a second chance in the spotlight. Fire Red and Leaf Green were generally remakes of the original games that started the franchise but now feature massive overhauls in gameplay including graphic improvements(like the previous games), return of all 150 original Pokémon as well as evolved version and baby versions previously inexistent during the time of the original games along with some of the newer generations, as well as gender option, weather changes, and club houses.
HeartGold and SoulSilver Version
Pokémon HeartGold and SoulSilver are the official spiritual successors of Gold and Silver version (much like Fire and Leaf succeeded Red and Green. Like their predecessors, Heart and Soul reintroduced features that were exclusive to previous games. They were the first games to re-utilize the "following Pokémon" feature that was first featured in the Yellow Pikachu Edition. This feature allowed the player to have one of their six Pokémon follow them much like Pikachu had in Yellow. However, this feature occasionally seemed unorthodox as Pokémon normally "ocean bound" can be selected to follow the player on land. Heart and Soul generally re-utilized all of the features that were carried over to Fire and Leaf. However, despite being the successors of Gold and Silver, Heart and Soul lacked the "time of day" feature that was exclusive to their predecessors. Heart and Soul was still praised for preserving the ability to travel from Johto to Kanto as well as the increase in the number of Pokémon featured in the game which ranges from the first generation to the fourth generation. In addition, Heart and Soul debuted the return of the Pokémon Walker which was prominent with its Game Boy Color counterparts.
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