The distribution of the Wifi Exclusive Mega Stones is set to end at the end of October, so if you miss out on them you will not be able to obtain them at all in Sun and Moon which removes the viability of many of these pokémon in terms of battle. To receive these Mega Stones, players have to download them using the Mystery Gift function. If you have not redeemed a Mystery Gift before the steps are simple.
-Select "Mystery Gift" when you start up the game.
-Select Get with Code/Password, then Yes, and then Yes again to connect to the Internet.
-Enter the code
-Confirm you want the gift and an animation will play.
-Speak to the deliveryman in any Pokémon Center to pick up your Mega Stones.
Each password can only be used once per game file, however, if you have multiple games you can redeem these passwords on each game. If you have received some or all of these Mega Stones from playing in tournaments hosted by the Pokémon Global Link, you can still download these too. Having a spare set of these to trade to a friend who misses out (or to Ultra Sun or Ultra Moon) would certainly be useful. Here are the passwords along with each Mega Stone you will receive from using them:
|M2DESCENT: This password gives players Mewtwonite X and Mewtwonite Y|
|INTIMIDATE: Mawilite, Beedrillite, Audinite, Medichamite|
|AZUL: Pidgeotite, Steelixite, Heracrossite, Houndoomite|
|MATSUBUSA: Blazikenite, Swampertite, Sceptilite, Cameruptite, and Banettite|
|SABLEVOLANT: Tyranitarite, Abomasite, Manectite, and Aggronite|
|POYONG: Galladite, Gardevoirite, Lopunnite, and Diancite|