Pokemon X and Y: Locations of all mega-stones

In order to collect all 25 megastones in "Pokemon X and Y", you have to play through the game once. Then you will find them here:

Mega stones can be found in Pokemon X and Y.

"Pokemon X" and "Pokemon Y" were released for the Nintendo 3DS in late 2013. With the mega stones you can turn your favorite Pokemons into a kind of Mega Pokemons. However, you can only find many megastones once you have defeated the "top four". These are marked with *** here.

1. Flunkifernite ***: It is located on the top floor of the Château Tristesse near the left staircase.
2. Gengarnit: Talk to the witch in Romantia City at the top left next to Team Flare Rüpel. In order for it to give you the megastone, you need a Pokedex entry from at least one Pokémon of the Gengar development series.
3. Despotarnit ***: Climb up to the right of the Relievera Arena entrance. Then switch to the climbing wall, which is located in the back right corner of the NPC. The megastone is only available in "Pokemon X".
4. Stollossnit ***: The Stollossnit is also available in the Relievera Arena, but only in "Pokemon Y". Climb up to the right of the Relievera Arena entrance. Then switch to the climbing wall, which is located in the back right corner of the NPC.
5. Simsalanit ***: When you enter the mirror cave on the bottom floor in the sunshine from Yantara City, go down the right stairs. Then it goes straight, up a hill. There you go down a small staircase on the left and the large staircase to the bottom floor. Follow the long corridor until you turn left at the end. In the mirror you see a passage, there you walk straight down through it. Finally, a sunbeam hits the floor in a room. You will find it right there.
6. Knakracknit ***: You will find the Knakracknit in the victory street to the left of the meeting point with Serena or Kalem in front of a tower with a smashing device.
7. Aerodactylonite: The location of the megastone is in the fossil laboratory in Petrophia. Talk to the right male researcher who will give you the aerodactylonite.
8. Scheroxnit ***: You can find the megastone in the frost cave behind the large Rexblisar, which also gives you the Rexblisarnit.
9. Pinsirnit ***: In the Nouvaria Forest you will discover the Pinsirnit after route two, near an entrance, in the grass. But only in "Pokemon X"
10. Skarabornnit ***: In "Pokemon Y" you will find the Skarabornnit in the same place in the Nouvaria Forest.
11. Hundemonnit ***: Look for two roller skaters on Route 16, below a large hill. But only in "Pokemon Y"!
12. Voltensonit ***: In "Pokemon X", on the other hand, the Voltensonit is hidden in the same place on Route 16.
13. Banetteonit ***: He is hiding in the "Chamber of Void".
14. Mewtunit X / Y: You can find him in Pokemon Village in a secret dungeon after catching Mewtu.
15. Ampharosnite: You get the ampharosnite for free! From an old man next to the angler in the Azure Bay, in front of the sea titan cave on a small island. You can surf there.
16. Kangamanite ***: You will discover the kangamanite in the light cave at the first turn on the right, at the end of a corridor.
17. Absolnit: After defeating your rival or rival in Batika City, he appears after the Pokemon League has ended. To do this, you must have completed at least one round in the battle house.
18. Meditalisnit ***: It is hidden in Romantia City in front of a fountain near the bridge to the left of the Pokecenter.
19. Guardevoirnit: After winning the top four, you will receive the megastone in Illumina City, in the red Café Soleil on the Südring.
20. Garadosnit ***: You will find it on a hill in southeastern Mosai. It is in the middle of a small waterfall.
21. Rexblisarnit: After defeating Team Flare members, you can get the megastone in the frost cave at Frescora when you contact Rexblisar.
22. Bisaflornite: a) After you defeat Professor Platan, you will get it in Illumina City if you choose Bulbasaur. It carries the megastone. b) Alternatively, you can buy it from a man in the stone boutique in Illumina City.
23. Turtoknit: a) After you defeat Professor Platan, you will get him in Illumina City if you choose Schiggy. It carries the megastone. b) Alternatively, you can buy it from a man in the stone boutique in Illumina City.
24. Charizard X / Y: After defeating Professor Platan, you will get it in Illumina City if you choose Charmander. It carries the megastone. b) Alternatively, you can buy it from a man in the stone boutique in Illumina City.
25. Lucarionite: In Yantara City, the megastone is hidden in the tower of knowledge. When you've defeated Arena Leader Connie, he'll be carried by the Lucario, who will then join the team.
26. Lohgocknit: The Lohgocknit was worn by the event flemmli, which was offered as a download gift at the end of 2013 when XY was published.

The best tips for catching Pokemons in "Pokemon X and Y" are easier to find than the megastones.