As with all Pokémon role-playing games released for handheld consoles, FireRed and LeafGreen are in third-person, overhead perspective. The main screen is an overworld, in which the player navigates the protagonist. Here a menu interface may be accessed, in which the player may configure his or her Pokémon, items, and gameplay settings. When the player encounters a wild Pokémon or is challenged by a trainer, the screen switches to a turn-based battle screen that displays the player’s Pokémon and the engaged Pokémon. During a battle, the player may select a move for his or her Pokémon to perform, use an item, switch his or her active Pokémon, or attempt to flee. All Pokémon have hit points (HP); when a Pokémon’s HP is reduced to zero, it faints and can no longer battle until it is revived. Once an enemy Pokémon faints, all of the player’s Pokémon involved in the battle receive a certain amount of experience points (EXP). After accumulating enough EXP, a Pokémon may level up.
Capturing Pokémon is another essential element of the gameplay. During a battle with a wild Pokémon, the player may throw a Poké Ball at it. If the Pokémon is successfully caught, it will come under the ownership of the player. Factors in the success rate of capture include the HP of the target Pokémon and the type of Poké Ball used: the lower the target’s HP and the stronger the Poké Ball, the higher the success rate of capture.
While FireRed and LeafGreen are remakes of Red and Green, they contain usability enhancements such as a contextual tutorial feature which allows players to look up data at any point in the game. Additionally, when continuing a saved game, players are shown the last four actions they performed, allowing them to remember what they were doing.
The games support the Game Boy Advance Game Link Cable, through which connected players may trade or battle. Players may also connect with Pokémon Ruby and Sapphire, as well as with Pokémon Colosseum, allowing them to obtain over 350 Pokémon. FireRed and LeafGreen also have the ability to connect to the Nintendo GameCube and interact with Pokémon Box: Ruby and Sapphire. In Box, the player may organize and view his or her collected Pokémon, and in Colosseum, Pokémon may be used in battle.FireRed and LeafGreen are also the first games in the series to be compatible with the Game Boy Advance Wireless Adapter, which comes prepackaged with the games. The adapter can be plugged into the link port of the Game Boy Advance system and allows players within a radius of 30–50 feet (9–15 meters) to wirelessly interact with each other. In addition, as many as 30 players at a time may join a special location called the “Union Room”, where they can trade, battle, or chat. Nintendo has set up “JoySpots” at Japanese retail locations for this purpose
Pokémon FireRed and LeafGreen takes place mostly in the fictional region of Kanto. This is one distinct region of many in the Pokémon world, which includes varied geographical habitats for the Pokémon species, human-populated towns and cities, and routes between locations. Some areas are only accessible once the player acquires a special item or one of the player’s Pokémon learns a special ability. Near the end of the plot, the protagonist is able to venture to the Sevii Islands, a new area not present in the original Red and Blue games. The Sevii Islands are an archipelago of seven islands and contain Pokémon normally exclusive to the Johto region, as well as several post-game missions. After the aforementioned missions on the Sevii Islands are completed, trading with Pokémon of the Hoenn region becomes available.
The silent protagonist of FireRed and LeafGreen is a child who lives in a small town named Pallet Town. After players start a journey and venture alone into tall grass, a voice warns them to stop. Professor Oak, a famous Pokémon researcher, explains to the player that such grass is often the habitat of wild Pokémon, and encountering them alone can be very dangerous. He takes the player to his laboratory where the player meets Oak’s grandson, another aspiring Pokémon Trainer. The player and their rival are both instructed to select a starter Pokémon for their travels. The rival then challenges the player to a Pokémon battle with their newly obtained Pokémon and continues to battle the player at certain points throughout the games.
After reaching the next city, the player is asked to deliver a parcel to Professor Oak. Upon returning to the laboratory, the player is presented with a Pokédex, a high-tech encyclopedia that records the entries of any Pokémon that are captured. Oak asks the player to fulfill his dream of compiling a comprehensive list of every Pokémon in the game.
While visiting the region’s cities, the player encounters special establishments called Gyms. Inside these buildings are Gym Leaders, each of whom the player must defeat in a Pokémon battle to obtain a Gym Badge. Once a total of eight badges are acquired, the player is given permission to enter the Pokémon League, which consists of the best Pokémon trainers in the region. There the player battles the Elite Four. Also throughout the game, the player has to fight against the forces of Team Rocket, a criminal organization that abuses Pokémon. They devise numerous plans to steal rare Pokémon, all of which the player must foil, meeting and defeating the organization boss Giovanni.
After the first time the player defeats the Elite Four, one of the members, Lorelei, disappears. After gaining access to the Sevii Islands, an entirely new region, the player discovers Lorelei in her house and convinces her to come back with him. Once more, the protagonist must thwart the Team Rocket’s plans on several occasions, recover two artifacts, the Ruby and the Sapphire, and put them in the main computer at One Island. After that, the player can communicate, battle, trade, etc., with Ruby and Sapphire