The official Pokémon website has revealed that Articuno, Zapdos and Moltres will be distributed via Serial code in the Pokémon Trainer Club newsletter.

Look for a Trio of Legendary Pokémon in Your Inbox!

A chance to get Articuno, Zapdos, and Moltres is arriving in the May Pokémon Trainer Club newsletter!

Be sure to check out the May Pokémon Trainer Club newsletter, where you'll find codes to get the Legendary Pokémon trio Articuno, Zapdos, and Moltres for your game! Enter these unique codes to unlock all three Pokémon in your Pokémon Omega Ruby, Pokémon Alpha Sapphire, Pokémon X, or Pokémon Y game. These Pokémon are special in that each one has its Hidden Ability, marking the first time you can get these Pokémon with this trait!

If you're already a Pokémon Trainer Club member, you can make sure you're eligible to receive the newsletter on your Pokémon Trainer Club settings page. Also, it's a good idea to check that email from Pokemon.com won't go into your junk mail folder.

If you're not yet a Pokémon Trainer Club member, there's never been a better time to join! In addition to the special codes for Pokémon video games and the Pokémon Trading Card Game Online, the newsletter will deliver exciting Pokémon news and information directly to your inbox. Plus, the Pokémon Trainer Club includes all kinds of other benefits, including a custom Trainer designer, access to the Pokémon Global Link, and more. And best of all, it's free! Sign up for the Pokémon Trainer Club today.

Be sure to sign up for the Pokémon Trainer Club newsletter by April 22, 2016, to be eligible to receive codes to get Articuno, Zapdos, and Moltres in May!

Also, don't miss the cinematic classic Pokémon the Movie 2000 on Pokémon TV featuring Articuno, Zapdos, and Moltres for a limited time.

Source: http://www.pokemon.com/us/pokemon-news/look-for-a-trio-of-legendary-pokemon-in-your-inbox/

Get the Legendary Pokémon Trio Articuno, Zapdos, and Moltres for Your Pokémon Video Game! - YouTube Trailer

Source: https://www.youtube.com/watch?v=z2vd1dfEbRA