Legendary Pokémon

Legendary Pokémon are group of Pokémon considered to be very rare and powerful. They cannot be obtained by catching them in the wild nor hatching from eggs. There are two primarily methods to capture Legendary Pokémon: defeat them in Raid Battle and then can catch them in Bonus Challenge or claiming Research Breakthrough. The Lake Guardians are the special cases available in wild. There are total of 26 Legendary Pokémon and 25 of them have been made available through the Raid Battles system currently.

Mythical Pokémon share similar characteristics, but their obtain method is different.

Characteristics
Legendary Pokémon share the following characteristics:
 * does not evolve from or into any other Pokémon
 * low catch rate, usually 2%
 * Buddy Pokémon 20 km for 1 candy
 * require 100,000 Stardusts and 100 candies to unlock the second Charged Attack
 * can be filtered in Pokémon search by typing legendary
 * an extra warning appears when trainers try to transfer them, cannot be mass transferred as well
 * require a Special Trade, cost a large amount of Stardust even if already registered by both trainers
 * cannot be assigned to Gym

Kanto
There are four Legendary Pokémon from Kanto region.

There are three Legendary Pokémon known as Legendary Birds, which are:

And a very powerful Psychic-type Pokémon - Mewtwo. It has an extra Armored Form.

Johto
There are five Legendary Pokémon from Johto region. They belong to two groups.

First group is known as Legendary Beasts, which are:

And two Flying-type Pokémon known as Tower Duo and they are:

Hoenn
There are eight Legendary Pokémon from Hoenn region. They belong to three groups.

The first group is called Legendary Titans, which are:

The second group is a duo of two Dragon, Psychic-Pokémon known as Eon Duo and it consists of:

The third group is known as Weather Trio and it consists of:

Sinnoh
There are nine Legendary Pokémon from Sinnoh region. Six of them belong to two groups.

First group is called Lake Guardians and consists of three Psychic-type Pokémon:

Second group of Legendary Pokémon is called Creation Trio. Giratina has two forms namely Altered Forme and Origin Forme.

Other Legendary Pokémon are Cresselia, Heatran and Regigigas, neither of them is related to each other. Regigigas is the master of Legendary Titans from Hoenn region.

Availability
The Lake Guardians are region-exclusive Pokémon regardless of wild or raid. Uxie is in the Asia-Pacific region. Mesprit is in Europe, the Middle East, Africa, and India. Azelf is in the Americas and Greenland.

x indicates the shiny variant was not available during that period.