Mega Diancie's amazing Attack, Special Attack, and STAB options in Moonblast and Diamond Storm make it the best mixed wallbreaker for Fairy teams. After Mega Evolving, Mega Diancie's Speed is incredible for a wallbreaker, and it is able to check fast attackers like Mega Charizard Y and Nihilego that are otherwise difficult for Fairy to deal with. Its huge movepool makes it unpredictable, and it has many coverage options that it can use. In fact, with Psychic, Mega Diancie is the best check to Poison teams and is the only reliable way to break their defensive core. Access to Stealth Rock allows Mega Diancie to support its team further, while setup moves like Rock Polish make Mega Diancie capable of sweeping on its own, expanding its possibilities. Unfortunately, Mega Diancie's bulk is rather terrible, and its Rock typing makes it weak to many priority users such as Azumarill and Mega Scizor. While base 110 Speed is very good against defensive teams, Mega Diancie is still easily outsped by offense teams if it doesn't have Rock Polish. When combined with its poor bulk, Mega Diancie is very easy to revenge kill. Lastly, Mega Diancie suffers from serious four-moveslot syndrome, as dropping a coverage move for utility leaves Mega Diancie walled by key threats, meaning its vast movepool cannot always be fully utilized.
Mega Diancie stands out as the best Mega Evolution and mixed attacker for Rock teams thanks to its fantastic Attack and Special Attack stats and great movepool. These traits are accompanied by an impressive 110 Speed stat, allowing Mega Diancie to outspeed threats such as Keldeo and Terrakion. Mega Diancie takes great advantage of its Attack stat with Diamond Storm, a powerful and reliable Rock-type STAB move with a 50% chance to increase its Defense by 2 stages. This can be very helpful against threatening physical attackers like Breloom and defensive Mega Scizor, since it survives an unboosted Bullet Punch when at +2 Defense. With Magic Bounce, Mega Diancie provides fantastic utility, bouncing back entry hazards such as Galvantula's Sticky Web as well as status moves like Thunder Wave and Will-O-Wisp. Its part-Fairy typing along with a strong Fairy-type STAB move in Moonblast allows it to beat threats to Rock teams such as Mega Sableye. Its great movepool also allows it to provide a plethora of helpful coverage. Unfortunately, Mega Diancie's terrible bulk and defensive typing make it largely vulnerable to common priority moves such as Aqua Jet and Bullet Punch. Even with Mega Diancie's fantastic Speed, it's still susceptible to revenge killers like Excadrill in sand, Tapu Koko, and Choice Scarf Jirachi. Mega Diancie also has difficulty fitting all of its beneficial coverage options onto a single set.
name: Offensive (Fairy)
move 1: Moonblast
move 2: Diamond Storm
move 3: Psychic / Earth Power
move 4: Stealth Rock / Hidden Power Fire
ability: Clear Body
evs: 4 Atk / 252 SpA / 252 Spe
Moonblast is a powerful STAB attack that 2HKOes most offensive Pokemon that don't resist it. Diamond Storm has great coverage with Moonblast and breaks most special walls like Alolan Muk and Zapdos, allowing Mega Diancie to be a powerful mixed wallbreaker. Psychic makes Mega Diancie one of the best checks to Poison teams, as it 2HKOes everything except for Alolan Muk. Earth Power can be used over Psychic, as it allows Mega Diancie to still hit many Poison-type Pokemon such as Toxapex but also targets Pokemon such as Mega Steelix that otherwise blow past Fairy teams. Mega Diancie's ability to easily force switches makes it a good user of Stealth Rock if nothing else on the team can bring it. Alternatively, Hidden Power Fire instead of Stealth Rock rounds off Mega Diancie's coverage by allowing it to hit Steel-types like Ferrothorn and Mega Scizor on the switch.
252 Speed EVs and a Naive nature are used to make Mega Diancie as fast as possible, outspeeding Alolan Ninetales and Keldeo and at least Speed tying with Latios and opposing Mega Diancie. All remaining EVs are put into Special Attack to maximize Mega Diancie's damage output. Clear Body prevents Intimidate and Sticky Web from reducing Diancie's stats before it Mega Evolves.
In most matchups, Diancie should Mega Evolve as early in the game as possible in order to gain Magic Bounce, allowing it to switch into many walls to reflect their utility moves. Against teams with Sticky Web or Toxic Spikes, this is especially important to protect the team. Do be aware that Diancie's defenses are much better before it Mega Evolves, so keep that option in mind to defeat Iron Head Skarmory and even take a hit from Mega Scizor if Reflect is up. Mega Diancie's bulk is not great, so avoid switching into attacks, as even when resisted, moves such as Victini's V-create deal serious damage to it. Instead, use double switches and Magic Bounce to bring it in safely. Use Mega Diancie to wallbreak early-game for its teammates. Weakening checks early on can also give Mega Diancie more room to play with later on, and this is especially important for sets with Rock Polish. Against Poison teams, try to keep Mega Diancie at full HP for as long as possible, as Mega Venusaur's Giga Drain cannot OHKO it and the healing doesn't prevent Mega Diancie's Psychic from 2HKOing it with Stealth Rock support. However, Diamond Storm 2HKOes Alolan Muk, and it may be worth taking a hit in order to take out Alolan Muk to sweep with Psychic. If Mega Diancie is using Stealth Rock, it can take advantage of its huge movepool as a lead in order to set the entry hazard immediately while the opponent scouts for coverage moves. Both Stealth Rock and Rock Polish are easily used whenever Mega Diancie comes in threatening to revenge kill a target; if hidden well until this point, their use can easily surprise your opponent and give you a huge advantage.
Klefki is an amazing teammate, as it provides Spikes support, allowing Mega Diancie to KO Mega Venusaur with Psychic even if it switches into Diamond Storm. Klefki's dual screen support is also incredibly useful, as it allows Mega Diancie to survive hits it wouldn't otherwise be able to in order to 2HKO most of the metagame. Tapu Bulu is another teammate that brings defensive support to Mega Diancie. With Grassy Terrain, Mega Diancie is actually capable of surviving even STAB Earthquake, and the healing is much appreciated. Tapu Bulu also takes on Ground and Water teams almost singlehandedly, making it almost an essential partner. Tapu Koko forms a powerful wallbreaking core with Mega Diancie, as Tapu Koko can break most Water-types and can handle most Steel-types as well if Mega Diancie lacks Hidden Power Fire. Azumarill tends to have trouble with Pokemon such as Mega Venusaur and Skarmory that Mega Diancie is very capable of luring in and removing. Clefable can carry Stealth Rock, enabling Mega Diancie to use a different move. Alternatively, if Mega Diancie still wants to use Stealth Rock, Clefable can use a Calm Mind set or even a utility move such as Knock Off. Clefable also often uses Babiri Berry + Fire Blast, which allows it to take out Mega Scizor for Mega Diancie. Togekiss can be another good anti-Steel option that can also use Defog to remove entry hazards that get past Mega Diancie's Magic Bounce.
name: Mixed Attacker (Rock)
move 1: Diamond Storm
move 2: Moonblast
move 3: Psychic
move 4: Hidden Power Fire
ability: Clear Body
evs: 16 HP / 240 SpA / 252 Spe
Diamond Storm is Mega Diancie's best Rock-type STAB move, being able to increase its Defense by 2 while also allowing it to beat specially defensive Pokemon like Zapdos and Mantine. This allows Mega Diancie to function as a mixed wallbreaker rather than a primarily special one. Moonblast is used to hit Fighting-, Dragon-, and Dark-types like Keldeo, Garchomp, and Mega Sableye. Psychic is a solid option alongside Diamond Storm, allowing Mega Diancie to effectively dismantle Poison's defensive core of Mega Venusaur, Toxapex, and Alolan Muk, specifically being able to 2HKO Mega Venusaur, which typically poses a threat to Rock teams. Hidden Power Fire allows Mega Diancie to hit Steel-types such as Skarmory and Ferrothorn, as well as hitting Mega Scizor on the switch. Earth Power is a good alternative, allowing Mega Diancie to KO Steel-types that aren't beaten by Hidden Power Fire, such as Heatran and Magnezone.
Maximum investment in Speed with a Naive nature allows Mega Diancie to outspeed Pokemon such as Landorus and Infernape. A Naive nature is chosen over Hasty because the former will allow Mega Diancie to always survive Mega Lopunny's High Jump Kick from full health. 16 EVs in HP are used to always survive Skarmory's Iron Head before Mega Evolving while 2HKOing it with Hidden Power Fire. However, if Earth Power is opted for, these EVs are unneeded. Before Mega Evolving, Mega Diancie will have the ability Clear Body, which makes it immune to stat decreases, which is especially helpful when coming in on Sticky Web. Upon Mega Evolving, it gains Magic Bounce, which allows it to bounce back status moves such as Toxic and Thunder Wave and entry hazards such as Stealth Rock and Sticky Web.
In most situations it's a good idea to lead with Diancie and Mega Evolve against entry hazard setters in order to bounce the hazards back, which is especially helpful against Galvantula's Sticky Web, since Rock teams don't use any hazard removers. If possible, always take the opportunity to revenge kill something with Diamond Storm, since Mega Diancie largely benefits from the +2 Defense increase. Since Mega Diancie's bulk isn't very good, try bringing it in after another Pokemon on your team has fainted. In matchups like Dark and Dragon, try to make smart doubles into Mega Diancie in order to shift more momentum on your side. In matchups like Fighting, Grass, and Poison where you need Mega Diancie to be as healthy as possible, don't let it take unnecessary damage before it encounters an important threat like Breloom or Mega Venusaur. Sometimes it's better to hold off on Mega Evolving to take advantage of regular Diancie's superior bulk to allow it to survive a Hidden Power Steel from Latios, as well as being unaffected by Sticky Web and Intimidate thanks to Clear Body. Avoid switching into powerful neutral or resisted attacks, especially after Mega Evolving. Try switching into passive Pokemon such as Klefki in order to bounce back status conditions and hazards.
Shuckle can set up Sticky Web for Mega Diancie to allow it to outspeed Choice Scarf users such as Terrakion and Heracross while also being able to halt setup sweepers like Mega Scizor and Azumarill with Encore. This frees a moveslot for Mega Diancie, since it won't have to rely on Rock Polish to outspeed most threats. In return, Mega Diancie can bounce back Stealth Rock to make sure Shuckle doesn't lose a quarter of its health upon switching in. Terrakion can break past defensive checks like Chansey and Porygon2 that would beat Mega Diancie otherwise while also being a solid revenge killer with a Choice Scarf, revenge killing threats like Hydreigon and +1 Mega Sharpedo. Tyranitar is a powerful physical wallbreaker that can set up sand for Mega Diancie, which boosts its Special Defense. It's also capable of trapping Latios and Gengar with Pursuit. Rhyperior and Alolan Golem are both capable of checking Mega Scizor for Mega Diancie. Rhyperior can serve as an effective physical blanket check against threats like Excadrill and Landorus-T, while Alolan Golem can trap and remove problematic Steel-types like Celesteela and Ferrothorn. Cradily can come in on Water-type attacks for Mega Diancie while also being able to beat Ground-types like Hippowdon, Seismitoad, and Choice Scarf Landorus-T. In return, Mega Diancie can check Fighting-types like Terrakion and Heracross while also bouncing back threatening status moves like Toxic. Omastar appreciates Mega Diancie keeping entry hazards away in order to be as healthy as possible while setting up with Shell Smash. It can also beat Ground-types like Hippowdon and Mamoswine with its Water-type STAB moves. Nihilego is a good secondary special wallbreaker that can beat Fairy- and Grass-types like Clefable, Tapu Bulu, and Celebi with its Poison-type STAB move. It can also use its helpful coverage to remove Water-types like Swampert and Mega Slowbro with Grass Knot and Thunderbolt respectively, as well as Ground-types like Landorus and Gliscor with Hidden Power Ice.
Calm Mind can be used to make Mega Diancie even more powerful, but it doesn't help Mega Diancie against offense, and Mega Diancie still cannot beat Chansey with it. Power Gem can be used alongside Calm Mind instead of Diamond Storm if desired. For all-out attacker sets, Hidden Power Ice is a viable option to beat Landorus and Gliscor, which Mega Diancie easily lures in. However, Skarmory will completely wall Mega Diancie in this case, and Mega Scizor can switch in without any fear. Nature Power can be a great option that lets Mega Diancie take out Ground-types such as Gastrodon when paired with Tapu Bulu's Grassy Surge. It can also be used with Tapu Koko's Electric Surge to 2HKO Celesteela and Water-types like Empoleon that otherwise give Mega Diancie trouble. However, these threats are already dealt with by the Island Guardian supporting Mega Diancie, so it tends to be redundant coverage for the team.
Rock Polish can be used to give Mega Diancie a chance to sweep offensive teams. However, this is usually unnecessary with the speed control offered by Shuckle’s Sticky Web. Calm Mind can be used in order to increase Mega Diancie's wallbreaking potential, always OHKOing Tapu Bulu at +1 with Moonblast. Power Gem can also synergize with this, doing much more significant damage against Mega Venusaur than Diamond Storm would. Outside of this, though, Mega Diancie finds more use from the extra coverage provided by Hidden Power Fire and Psychic, and Diamond Storm is the preferred Rock-type STAB move in order to KO specially defensive Pokemon like Zapdos and Mantine more easily as well as obtain a helpful Defense boost. Hidden Power Ice can be used as a means of KOing Landorus and Gliscor. However, this would come at the cost of Hidden Power Fire, making Mega Diancie unable to 2HKO Skarmory and Ferro
Checks and Counters
**Gastrodon**: Specially defensive Gastrodon counters Mega Diancie, as it switches into any attack and threatens to KO back with its STAB attacks.
**Mixed Walls**: Certain mixed walls such as Chansey and Porygon2 completely counter Mega Diancie and can slowly wear it down. They do need to be careful of Magic Bounce reflecting their status moves, though.
**Trapping**: Dugtrio can trap Mega Diancie and remove it with Arena Trap and Earthquake.
**Steel-types**: Most Steel-types can survive at least one Hidden Power Fire and OHKO back. Mega Scizor is particularly good thanks to Bullet Punch, and Celesteela can switch into any move even when Stealth Rock is up.
**Ground-types**: Bulky Ground-types such as Hippowdon can easily take any one hit from Mega Diancie, and offensive Ground-types like Excadrill can outspeed it and OHKO it.
**Water-types**: Water-types that outspeed Mega Diancie, such as Choice Scarf Keldeo and Kingdra in the rain, are capable of forcing it out with the threat of their super effective STAB attacks.
**Gastrodon**: Gastrodon is one of the most consistent defensive answers to Mega Diancie, not fearing any of its attacks and being able to use Recover to heal any lost damage while wearing Mega Diancie down with Scald and Earthquake.
**Defensive Pokemon**: Chansey and Porygon2 are never 2HKOed by any of Mega Diancie's attacks and can use their recovery to wear down Mega Diancie while keeping themselves healthy. However, with Calm Mind, Mega Diancie is able to beat Porygon2.
**Steel-types**: Steel-types like Mega Scizor and Choice Scarf Jirachi can beat Mega Diancie with their respective STAB moves.
**Water-types**: Water-types like Kingdra, Mega Swampert, and Greninja are able to outspeed and KO Mega Diancie. However, none of these Pokemon will appreciate switching into a Moonblast.
**Grass-types**: Grass-types like Choice Scarf Tapu Bulu and Rotom-C can outspeed and KO Mega Diancie with their Grass-type STAB moves. Tapu Bulu KOes even after Mega Diancie has a Defense increase, and Rotom-C is unaffected by Shuckle's Sticky Web.
**Ground-types**: Ground-types like Excadrill and Dugtrio can outspeed Mega Diancie and remove it with their STAB attacks. Dugtrio in particular can make sure Mega Diancie is unable to switch out thanks to Arena Trap.
**Revenge Killers**: Choice Scarf Keldeo and Tapu Koko are capable of outspeeding and KOing Mega Diancie, despite not being able to come in on a Moonblast.
- Written by: [[Eien, 100418], [smub, 397606]]
- Fairy analysis by: [[Eien, 100418]]
- Rock analysis by: [[smub, 397606]]
- Translated by: [[username, id]]
- Italian grammar checked by: [[username, id], [username, id]]
- Quality checked by: [[Kev, 314540], [iLlama, 296591], [Izaya, 311872], [Moosical, 215618], [terrors, 279058]]
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