Besides the leap to 3D, Mega Evolutions were one of the most widely promoted elements of the newest Pokemon game--if you read our Pokemon X and Y review, you already knew that. Because of a reason explained by the story that we won't spoil in case you actually care about the stories in Pokemon games, the Kalos region is lousy with Mega Stones. Thankfully, some wise individuals have found out how to use their power to allow specific Pokemon to evolve mid-battle into new, awesome forms.
While some of them are literally handed to you on your path to becoming a Pokemon Champion, others require you to speak to specific people. Others, yet, are even harder to find. Thankfully, we've got you covered with a guide to getting every single one. Also be sure to check out our full, totally complete Pokemon X and Y Pokedex for a look at every single new monster.
Charizard: Professor Sycamore gives you Charizardite X or Y when he gives you the Pokemon, depending on your version of the game. If you didn't get one from Professor Sycamore, you're able to buy it from a man for 100,000 in the Stone Emporium in Lumiose City every three days (his stock changes every day) after you finish the game.
Blastoise: Professor Sycamore gives you Blastoisite when he gives you the Pokemon. If you didn't get one from Professor Sycamore, you're able to buy it from a man for 500,000 in the Stone Emporium in Lumiose City every three days (his stock changes every day) after you finish the game.
Venusaur: Professor Sycamore gives you Ivysaurite when he gives you the Pokemon. If you didn't get Venusaurite from Professor Sycamore, you're able to buy it from a man for 300,000 in Lumiose City (his stock changes every day) after you finish the game.
Lucario: Korrina gives you Lucarioite when she gives you the Pokemon. Hey! Everyone! Free Lucario at Korrina's house!
Abomasnow: After saving an Abomasnow in the Frost Cavern you're given Abomasnowite.
Ampharos: Travel beneath the Sea Spirits Den in Azure bay, and a man on an island (next to a fishing trainer) will give you Ampharosite.
Gengar: In Lavarre City a black-haired woman at the top left of the city will give you a Gengarite.
Aerodactyl: Talk to the scientist on the right side of the Fossil Lab in Ambrett town to get your shiny new Aerodactylite.
Absol: Defeat your rival in Kiloud city and you'll receive an Absolite.
Mewtwo: Capture Mewtwo in the cave to the west of the Pokemon Village and you'll get Mewtwoite X or Mewtwoite Y depending on your version of the game.
Gardevoir: Trade a Pokemon (any will do) with Diantha in the cafe to the south in Lumios City where you first met her. She'll give you a Pokemon holding Gardevoirite.
This is where things get tricky. After completing a few "go here, do this" missions after beating the Elite Four, you're given the ability to find Mega Stones at night. Between 8PM and 9PM (real time), you're sent off to find locations around the world where the ground is sparkling. If you interact with these spots, you'll get a Mega Stone. The rest of the day? They're simply not there.
Alakazam: There's a spot in the Reflecting Cave where there's a glowing landing--you likely thought there'd be a Legendary Pokemon when you came here earlier. Nope! It's a Alakazite.
Aggron: In version Y, go to Cyllage City gym (the rock climbing one) and head to the second level to the right. After climbing, you'll find Aggronite.
Banette: Head over to the Chamber of Emptiness for your Banetteite--turns out it's not so empty, is it?
Garchomp: Near the end of Victory Road there's a small area outside, and there's a stone tower at the top left. Use Rock Smash and walk in front of it for your Garchompite.
Gyrados: In the southeast part of Couriway Town there are a bunch of rivers near a waterfall--here, you can find the Gyradosite.
Heracross: In version Y, go into Santalune Forest from Route 2. Go straight up and Heracrossite is on the left in the tall grass.
Houndoom: Leave Dendemille town towards Route 15 and go south--you'll find yourself on Route 15. Follow the path until you see two skaters circling a large rock, below that rock will be Houndoominite if you have Y.
Kangaskhan: Head to the Glittering Caves by way Ambrett town (after riding the Rhydorn on the path South of the town). Once inside, take the first right--Kangaskhanite is at the end of the path.
Manectric: Leave Dendemille town towards Route 15 and go south--you'll find yourself on Route 15. Follow the path until you see two skaters circling a large rock, below that rock will be Manectricite if you have X.
Mawile: On the second floor of Shabboneau Castle, (on the left) you can find Mawilite. Yes, it's indoors.
Medicham: In front of the well in Laverre City, Medichamite is sparking on the ground.
Pinsir: In version X, go into Santalune Forest from Route 2. Go straight up and Pinsir is on the left in the tall grass.
Scizor: Behind the Abomasnow in the Frost Cavern you'll find Scizorite. It's hard to see--but it's there.
Tyranitar: In version x, go to Cyllage City gym (the rock climbing one) and head to the second level to the right. After climbing, you'll find Tyranitarite.
Blaziken: You can't actually get it in-game--it comes with the Torchic that comes free. On the main menu, select Mystery Gift, then Receive Gift, then Yes, then Get Via Internet, then Yes. Then go into the game and talk to the woman to the left of the desk in any Pokemon Center. You'll get a Torchic and Blazikenite for when it's all growed up.
As far as we know, this is all of them. If you have any questions leave them in the comments, below, and we'll help you find the Mega Stones you need!