Mega Pokémon that are Special attackers:
Venusaur, Blastoise, Charizard Y, Alakazam, Gengar, Mewtwo Y, Ampharos, Houndoom, Gardevoir, Manectric, Absolº, Lucarioº, Abomasnow, Pidgeot, Slowbro, Sceptile, Camperupt, Altaria, Salamenceº, Latios, Latias, Diancie†
º usually run a Physical set
† run a Mixed set
Mega Pokémon that are dedicated Special attackers:
Blastoise, Charizard Y, Alakazam, Gengar, Mewtwo Y, Houndoom, Gardevoir, Pidgeot, Sceptile, Camerupt, Altaria, Latias, Diancie
Mega Pokémon that are bulky/semi-bulky Special attackers
Blastoise, Charizard Y, Mewtwo Y, Gardevoir, Altaria, Latias, Diancie
Okay, now that's done. We have narrowed down the special-based Mega Evolutions to those who can tank more than one non-supereffective hit. This leaves us with Blastoise, Charizard Y, Mewtwo Y, Gardevoir, Altaria, Latias and Diancie. I will provide movesets for each of them and offer a brief explanation of how they work and how to get them.
Ability: Rain Dish > Mega Launcher
EVs: 252 HP / 252 SpA / 4 Def
- Dark Pulse
- Hydro Pump
- Dragon Pulse
- Aura Sphere/Rapid Spin
Obtained: Given to you in Pokémon XY, Wonder Trade, GTS
Details: Mega Blastoise is a tank. Mega Launcher boosts the powe rof Pulse and Sphere moves. Dark Pulse, Aura Sphere and Draogon Pulse are coverage and boosted by Mega Launcher. Hydro Pump is chosen over Water Pulse due to more power. Aura Sphere can only be obtained via breeding, so Rapid Spin is a useful support move.
Mega Charizard Y
Charizard@ Charizardite Y
Ability: Blaze > Drought
EVs: 252 SpA / 252 Spe / 4 Def
- Air Slash
- Heat Wave/Fire Blast
Obtained: See Blastoise
Details: Mega Charizard Y is surprisingly bulky with 78/78/115 defences, able to survive most non-supereffective Special moves. SolarBeam is insta-charged in the Sun and eliminates Water- and Rock-types. Air Slash is STAB and Protect lets you guard against Stone Edges. Heat Wave and Fire Blast are boostedd by the Sun, but Heat Wave has better accuracy and Fire Blast has better power.
Mega Mewtwo Y
Mewtwo@ Mewtwonite Y
Ability: Pressure > Insomnia
EVs: 252 SpA / 252 Spe / 4 SDef
- Ice Beam
- Focus Blast
Obtained: Capturable in Pokémon XY, GTS
Details: Mega Mewtwo Y has respectable bulk and wicked Sp. Attack. It is so strong that before the release of Mega Rayquaza, the only thing in Ubers that could hope to OHKO it was Yveltal's Sucker Punch. Psystrike is STAB while Ice Beam and Focus Miss are coverage. Recover is to give Mewtwo a longer lifespan.
Ability: Synchronize > Pixilate
EVs: 232 SpA / 24 Def / 252 Spe
- Hyper Voice
- Calm Mind
- Focus Blast/Shadow Ball
Obtained: Route 102
Details: Mega Gardevoir hits like a truck. Pixilate turns Hyper Voice into a STAB Fairy attack. Psyshock is secondary STAB. Calm Mind buffs her Special side and Focus Blast or Shadow Ball is for coverage.
Ability: Cloud Nine > Pixilate
EVs: 252 HP / 196 SpA / 60 Spe
- Hyper Voice
- Fire Blast
- Draco Meteor
Obtained: Route 114, Route 115, Sky Pillar
Details: Mega Altaria is essentially a bulkier Mega Gardevoir. Hyper Voice is Pixilate STAB as well as Draco Meteor. Fire Blast helps her not to be walled by Steel-types and Roost is for a reliable 50% recovery.
EVs: 72 HP / 184 SpA / 252 Spe
- Calm Mind
- Stored Power
Obtained: Captured in-game
Details: Mega Latias is bulky as heck. It's standard Calm Mind + Stored Power set can sweep teams if you get her set up. Stored Power gets stronger the more you use Calm Mind. Thunderbolt is coverage, and Roost is reliable recovery.
Ability: Clear Body > Magic Bounce
EVs: 252 Spe / 252 SpA / 4 Atk
- Earth Power
- Diamond Storm
- Hidden Power [Fire]/Psyshock
Obtained: Event, Wonder Trade (it's happened before)
Details: Mega Diancie is a huge step up from regular Diancie. It gets a fantastic ability in Magic Bounce and has two great STAB attacks. The only problem is its rarity. Diamond Storm and Moonblast are STAB, while Earth Power covers Steel-types. Hidden Power [Fire] and Psyshock are just two of the many coverage moves that can go in the final moveslot.