Pokémon involves catching and training of fictional creatures called "Pokémon" and using them to battle other Trainer's pokémon. Each successive generation of games builds upon this concept by introducing new Pokémon items, and gameplay concepts.
Game structure
Each game in the Pokémon series takes place in a fictional region of the Pokémon world, typically based on a real-world location, and begins with the player receiving a starter Pokémon, usually from that region's Pokémon Professor. Players have the option to choose one of three different types of Pokémon: a Grass type, a Fire type, and a Water type, though many starter Pokémon gain an additional type upon evolution. Many games include a rival character, who receives the Pokémon whose type is advantageous against the player's starter Pokémon. By traveling around the region, catching and evolving Pokémon, and defeating other Trainers in battle, the player increases the size and strength of their Pokémon collection. A major subplot of most games is to defeat a criminal organization, whose intents are usually trying to take over the world through the misuse of the game's legendary Pokémon.
Various facilities can be found throughout the Pokémon world such as Pokémon Centers, Poké Marts, and in Pokémon Sun and Moon, some trial locations and Gyms. At a Pokémon Center, the player can have their Pokémon healed for free and access the PC, where players can organize their collection of Pokémon, store and withdraw items, and have their Pokédex rated. Before X and Y, this is also where players can link up with other game cartridges or cards to battle or trade with other players. Poké Marts are shops where players can buy items with the money they win during battles; certain cities may have specialized shops, like a pharmacy or a department store. Periodically, a town will contain a Pokémon Gym, which houses a powerful Trainer known as a Gym Leader that functions as a boss. Victory against them grants the player a Gym Badge; after collecting eight Gym Badges, the player may challenge the region's Elite Four and Champion (in Pokémon Sword and Shield, the Elite Four is replaced by the Champion Cup, a single-elimination tournament that determines who gets the right to challenge the Champion). Gyms are absent in Sun, Moon, Ultra Sun, and Ultra Moon, being replaced by trials that serve a similar purpose.
Once the player completes the goal of conquering all 8 Gyms (or all Trials) or if the player's Pokémon are strong enough, the player then learns more about the legend of the region and can open the opportunity to summon, battle, and catch the mascot Legendary Pokémon at a certain location. Additionally, completing the main storyline opens up other features in the games; this is primarily done by allowing passage into otherwise inaccessible places. Many games also have facilities dedicated to battling, such as the Battle Frontier, Battle Tower, and Battle Maison. Afterward, the game remains virtually open-ended, with the ultimate goal of the player being to obtain at least one member of each of the different species of Pokémon, thus completing the Pokédex.
Pokémon battles
Battles between Pokémon are the central game mechanic of the Pokémon games. Within the game, they are used to train Pokémon to gain experience and become stronger, earn prize money, and to progress through the game's story. Battles can also be done between players by connecting two game systems.
Pokémon uses a turn-based system. When the player challenges a Trainer or encounters a wild Pokémon, the screen changes to a battle scene displaying the player's Pokémon, the opposing Pokémon, their respective HP bars, and an options menu. The player may carry between one and six Pokémon in their active party; the first Pokémon in the lineup is automatically sent into battle. At the start of each turn, both sides may use a move, use an item, switch their active Pokémon out for another in their party, or attempt to flee from battle (only when battling a wild Pokémon; the player cannot flee from battles against other trainers). If both sides use a move, the Pokémon who acts first is determined by Speed, although some moves, items, and effects can override this. If either side chooses any other option, that action is performed before the attacks.