Legendary Bird Trio: Articuno, Zapdos, Moltres

The Legendary Pokemon list begins with none other than Legendary Bird Trio, including Articuno, Zapdos, and Moltres. These birds are residents of Kanto Region, and are also commonly known as Winged Mirages. Each of them are associated with a given season within the real world, excluding autumn, and they each have a more bulkier, defensive niche in competitive play with higher Special Attack.

In the anime, these three birds weren't seen too much. Their claim to fame was in the Special where they were distubred and incessantly fighting each other, only to be stopped with the help or Lugia and the Chosen One (Ash Ketchum).

The Legendary Bird Trio are found in Pokemon Red/Blue/Yellow, Fire Red/Leaf Green, Platinum, Heart Gold/Soul Silver, and X/Y.

#144 - Articuno: Articuno can be found deep within the Seafoam Islands in first generation Games, along with the first and second generation remakes. In Pokemon Platinum and X/Y, it can be found roaming the given region (Only if you chose Chespin as your Starter in X/Y). After a number of encounters in X/Y, it will finally settle in the Spirit Den.

#145 - Zapdos: Zapdos can be found either within or outside the Power Plant in first generation Games, along with the first and second generation remakes. Like Articuno, in Pokemon Platinum and X/Y, it can be found roaming the given region (Only if you chose Fennekin as your Starter in X/Y). After a number of encounters in X/Y, it will finally settle in the Spirit Den.

#146 - Moltres: Unlike its counterparts, Moltres can be found in a number of places in the Games that it is found. It can be found deep within Victory Road in first generation games, Mt. Ember in the first generation remakes, and Mt. Silver in the second generation remakes. But much like its two counterparts, in Pokemon Platinum and X/Y, it can be found roaming the given region (Only if you chose Froakie as your Starter in X/Y). After a number of encounters in X/Y, it too will finally settle in the Spirit Den.