Pokémon (JP) (a portmanteau of "Pocket Monsters" (JP)) referred to the creatures that can be obtained in the highly successful Pokémon franchise. Currently, there are a total of 905 identified types of Pokémon species, with about 100 or so new ones being introduced with each new generation, or series of the games. In the first generation, which consisted of Pokémon Red and Blue, and the counterpart Pokémon Yellow, there were a total of 151 Pokémon.
Each Pokémon is categorized into a multitude of traits, including their type, color, weight, height, and so forth. Most Pokémon can evolve into a more powerful species by leveling up, sort of like how a character in a traditional RPG can change into a more powerful level.
Pokémon in the anime, have been shown to only be able to speak their name or a variation of it, excluding a select few who are capable of human speech (example - Meowth). Others, such as Mewtwo and the popular Lucario can speak telepathically, but not directly to a human.
Variation within species
There are a number of Pokémon with differences between genders. Most of these are some small differences, but some of these a are completely separate species of Pokémon like Tauros and Miltank. Gender variation was not introduced until the fourth generation. Oddly, after the fourth generation, the amount of gender differences has greatly decreased but, the degree of difference of these Pokémon are much larger than the majority of them. There are certain Pokémon that are the same species but, have different movesets depending on the gender.
Some Pokémon can only evolve if they are a certain gender.
Introduced in the seventh generation, certain Pokémon have regional differences based the region they are found in. These regional variants have developed differently based on the environment with most changing type, ability and can even evolve into completely separate Pokémon.
Starter Pokémon is a terminology concept that refers to Pokémon that the player must choose between in the beginning of each Pokémon video game.
Baby Pokémon are Pokémon at the lowest stage of Pokémon Evolution that cannot themselves breed.
Fossil Pokémon are Pokémon revived from fossils.
Pseudo-legendary Pokémon are Pokémon that has a three-stage evolution line, 1,250,000 experience at level 100, and a base stat total of exactly 600. Pseudo-legendary Pokémon are often more powerful than many other non-Legendary Pokémon due to their high base stats.
Legendary Pokémon tend to be the most powerful types. They're usually the mascots of a particular game and are found near the end of the playable character's adventure where they'll be given the chance to actually capture it.
Mythical Pokémon, also known as Event Legendaries, are a subset of Legendary Pokémon who are usually only available from Events.
Ultra Beasts are a group of extradimensional Pokémon originating from Ultra Space. They possess power that transcends humans' understanding of the world.
Some Pokémon have the ability to get stronger than their final evolution. It requires "a certain bond with their trainer" and a special stone called a Mega Stone. This is called a Mega Evolution. The Pokemon are stronger than their normal forms and often change many features, abilities and their form. After a battle finishes, they return to their normal form. This was introduced in Generation 6 with Pokémon X and Y.