All Mega Stone Locations in Pokemon Legends Z-A
Mega Meganium
Meganiumite
Obtained during Main Mission 10 if you chose 
Chikorita as your Pokemon Legends: Z-A starter Pokemon. Otherwise, it can be purchased from the Stone Emporium after completing Main Mission 37.
Mega Emboar
Emboarite
Obtained during Main Mission 10 if you chose Tepig as your starter Pokemon. Otherwise, it can be purchased from the Stone Emporium after completing Main Mission 37.
Mega Feraligatr
Feraligite
Obtained during Main Mission 10 if you chose Totodile as your starter Pokemon. Otherwise, it can be purchased from the Stone Emporium after completing Main Mission 37.
Mega Beedrill
Beedrillite
Defeat Rogue Mega Beedrill (Main Mission 16).
Mega Pidgeot
Pidgeotite
Exchange for 180 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Ampharos
Ampharosite
Defeat Rogue Mega Ampharos (Main Mission 23).
Mega Gyarados
Gyaradosite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Barbaracle
Barbaracite
Defeat Rogue Mega Barbaracle (Main Mission 22).
Mega Starmie
Starminite
Defeat Rogue Mega Starmie (Main Mission 34).
Mega Floette
Floettite
Win 15 battles in the Infinite ZA Royale.
Mega Pyroar
Pyroarite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 37.
Mega Clefable
Clefablite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 31.
Mega Alakazam
Alakazite
Exchange for 360 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Gengar
Gengarite
Purchase from the Stone Emporium for ₽50,000 after completing Main Mission 10.
Mega Scolipede
Scolipite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 25.
Mega Victreebel
Victreebelite
Defeat Rogue Mega Victreebel (Main Mission 13).
Mega Medicham
Medichamite
Purchase from the Stone Emporium for ₽50,000 after completing Main Mission 10.
Mega Manectric
Manectite
Exchange for 180 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Gardevoir
Gardevoirite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 25. Also available through Mystery Gift via the “Get via Internet” option.
Mega Gallade
Galladite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 25.
Mega Houndoom
Houndoomite
Exchange for 180 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Altaria
Altarianite
Defeat Rogue Mega Altaria (Main Mission 28).
Mega Audino
Audinite
Exchange for 180 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Lopunny
Lopunnite
Exchange for 180 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Banette
Banettite
Defeat Rogue Mega Banette (Main Mission 18).
Mega Camerupt
Cameruptite
Defeat Rogue Mega Camerupt (Main Mission 12).
Mega Excadrill
Excadrite
Exchange for 360 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 15.
Mega Garchomp
Garchompite
Purchase from the Stone Emporium for ₽70,000 after completing Main Mission 10.
Mega Sableye
Sablenite
Exchange for 180 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Mawile
Mawilite
Defeat Rogue Mega Mawile (Main Mission 21).
Mega Absol
Absolite
Defeat Rogue Mega Absol (Main Mission 9).
Mega Lucario
Lucarionite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Slowbro
Slowbronite
Defeat Rogue Mega Slowbro (Main Mission 11).
Mega Sharpedo
Sharpedonite
Exchange for 180 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Eelektross
Eelektrossite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 15.
Mega Dragonite
Dragoninite
Defeat Rogue Mega Dragonite (Main Mission 32).
Mega Venusaur
Venusaurite
Defeat Rogue Mega Venusaur (Main Mission 29).
Mega Charizard X
Charizardite X
Purchase from the Stone Emporium for ₽100,000 after completing Main Mission 10.
Mega Charizard Y
Charizardite Y
Purchase from the Stone Emporium for ₽100,000 after completing Main Mission 10.
Mega Blastoise
Blastoisinite
Purchase from the Stone Emporium for ₽100,000 after completing Main Mission 10.
Mega Malamar
Malamarite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 37.
Mega Dragalge
Dragalgite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 31.
Mega Glalie
Glalitite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 15.
Mega Froslass
Froslassite
Defeat Rogue Mega Froslass (Main Mission 27).
Mega Abomasnow
Abomasite
Purchase from the Stone Emporium for ₽50,000 after completing Main Mission 10.
Mega Scizor
Scizorite
Purchase from the Stone Emporium for ₽50,000 after completing Main Mission 10.
Mega Pinsir
Pinsirite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 15.
Mega Heracross
Heracronite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Hawlucha
Hawluchanite
Defeat Rogue Mega Hawlucha (Main Mission 17).
Mega Scrafty
Scraftinite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 31.
Mega Chandelure
Chandelurite
Exchange for 360 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 20.
Mega Aerodactyl
Aerodactylite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Steelix
Steelixite
Purchase from the Stone Emporium for ₽70,000 after completing Main Mission 10.
Mega Aggron
Aggronite
Exchange for 360 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 20.
Mega Tyranitar
Tyranitarite
Defeat Rogue Mega Tyranitar (Main Mission 33).
Mega Greninja
Greninjite
Participate in Season 1 of Ranked Battles.
Mega Falinks
Falinksite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 20.
Mega Chesnaught
Chesnaughtite
Participate in Season 3 of Ranked Battles.
Mega Skarmory
Skarmorite
Exchange for 240 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 25.
Mega Delphox
Delphoxite
Participate in Season 2 of Ranked Battles.
Mega Salamence
Salamencite
Exchange for 360 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 31.
Mega Kangaskhan
Kangaskhanite
Purchase from the Stone Emporium for ₽70,000 after completing Main Mission 10.
Mega Drampa
Drampanite
Exchange for 360 Mega Shards at the Quasartico Mega Shard Exchange.
Mega Metagross
Metagrossite
Exchange for 360 Mega Shards at the Quasartico Mega Shard Exchange after completing Main Mission 31.
Mega Zygarde
Zygardite
Obtained during Main Mission 37.
Mega Diancie
Diancite
Obtained during the Shine Bright Like a Gemstone EX Mission, which is unlocked via Mystery Gift.
Mega Mewtwo X
Mewtwonite X
Obtained during the Project M EX Mission, which is unlocked via Mystery Gift.
Mega Mewtwo Y
Mewtwonite Y
Obtained during the Project M EX Mission, which is unlocked via Mystery Gift.