Starting August 13th, 2014, players can receive a Heracross for their Pokémon X game or Pinsir for their Pokémon Y game. Initially these Pokémon will not have any held items but from August 18th, 2014 until August 31st, 2014, players can go to participating GameStop stores in the United States to get Mega Stones for the Pokémon to hold!

Look for a flyer at GameStop that contains a serial code. When players enter the code into their game, they'll receive the matching Mega Stone: Heracronite in Pokémon X or Pinsirite in Pokémon Y. GameStop will also be distributing a special preorder bonus poster for those that preorder a copy of Pokémon Omega Ruby or Pokémon Alpha Sapphire.

Heracross and Pinsir Distribution Instructions

You can receive Heracross or Pinsir via the Internet directly into your game. Follow these steps to receive the Pokémon!

1. Connect your system in the Nintendo 3DS family to the Internet.
2. Select MYSTERY GIFT on the main menu.
3. Select RECEIVE GIFT, then YES.
4. Select GET VIA INTERNET, then YES.
5. Watch as you receive Heracross (Pokémon X) or Pinsir (Pokémon Y)!
6. Speak to the delivery girl in any Pokémon Center to add Heracross or Pinsir to your party.
7. Be sure to save your game!

Source: http://www.pokemon.com/us/pokemon-news/unleash-the-strength-of-two-tough-pokemon/

Canadian Distribution

The Pokémon Global Link website has posted the information for this distribution for Canadians. Unlike the United States, players in Canada can receive Heracross for their Pokémon X game or Pinsir for their Pokémon Y game via the Nintendo Network starting on August 13th, 2014. Sometime in September, a Pokémon Trainer Club newsletter containing a special code will be sent to Canadian accounts so that they can also get Mega Stones for the Pokémon to hold.

Source: http://3ds.pokemon-gl.com/information/3ade2b4a-0c41-41ab-8572-be7e8a223084