Gen 6 Victim of the Week - ORAS Edition (Week 14 - 3 Attacks Mewtwo-Mega-X)

[Haunted Diamond]

Reserving Choice Scarf Terrakion

 

[yohoE]

thanks for the submissions n_n

next up for week 10 we have...

Week 10: A new addition to ORAS, Mega Diancie!

Diancie-Mega @ Diancite
Ability: Magic Bounce
EVs: 80 Atk / 252 SpA / 176 Spe
Naive Nature
- Calm Mind
- Moonblast
- Diamond Storm
- Earth Power
​

DON'T RESERVE SOMETHING AND THEN NOT DO IT....... TRY AND DO IT RIGHT AFTER YOU RESERVE IT..............

 

[brokenwings]

Mega Scizor (Counter)

Scizor-Mega @ Scizorite
Ability: Technician
EVs: 248 HP / 16 Def / 244 SpD
Adamant Nature
- Bullet Punch
- Roost
- Toxic
- U-turn / Pursuit / Superpower / Defog

Switches into any of Diancie's moves and roosts off the damage or threatens it with a 4x effective STAB priority move. The defense investment lets Scizor live 2 Diamond Storms after Stealth Rocks 100% of the time, and an Adamant nature ensures that Bullet Punch always OHKOs Diancie at +1 Defense. Toxic is for statusing switch-ins, the last moveslot is just filler.

calcs

80 Atk Mega Diancie Diamond Storm vs. 248 HP / 16 Def Mega Scizor: 127-150 (37 - 43.7%) -- guaranteed 3HKO after Stealth Rock

0+ Atk Technician Mega Scizor Bullet Punch vs. +1 0 HP / 0 Def Mega Diancie: 252-300 (104.5 - 124.4%) -- guaranteed OHKO

252 SpA Mega Diancie Earth Power vs. 248 HP / 240 SpD Mega Scizor: 92-109 (26.8 - 31.7%) -- 52.2% chance to 3HKO after Stealth Rock

 

[Dilwar]

Reserving Arceus-Ground imo

 

[kingmidas]

Bronzong @ Life Orb
Ability: Levitate
EVs: 252 HP / 252 Attack / 4 Sdef
IVs: 0 Spd
Brave Nature
-Trick Room
-Gyro Ball
-Earthquake
-Explosion
Offensive otr bronzong is sexy af as it checks xerneas/diancie really well and hits hard as shit until you need to boom to nuke everything.
Calcs are dumb because this is guy resists all attacks and easily KOs

 

[Mr.378]

Reserving Arceus-Steel

 

[Didoy75]

reserving jirachi genesect

 

[PoweredByRevenge]

Reserving primal kyogre.

I will finish this tomorrow night since i have no time rn don't worry yohoe :]

e: done today ;)

 

[Dilwar]

Counter

Arceus-Ground @ Earth Plate
Ability: Multitype
EVs: 80 HP / 252 Atk / 176 Spe
Jolly Nature
- Earthquake
- Stone Edge
- Swords Dance
- Recover

Kinda standard offensive Groundceus I guess. It outspeeds M-Diancie and picks up an easy OHKO, as well as living any 2 hits from it after SR damage. The EVs outspeed 110s which includes Lati@s, Gengar pre-mega and all variants of M-Diancie itself. 80HP ensures it lives 2 Moonblasts after SR damage, so if stuff like Tailwind or Sticky Web is up, this could still be a counter. The rest was just dumped into attack. The moveset is pretty self-explanatory, with Recover over something like Extremespeed to allow this to counter Diancie for the entire battle.

M-Diancie VS Groundceus

252 SpA Mega Diancie Moonblast vs. 80 HP / 0 SpD Arceus-Ground: 156-184 (38.9 - 45.8%) -- guaranteed 3HKO after Stealth Rock

(Don't think I have to calc Earth Power or Diamond Storm for obvious reasons).

Groundceus VS M-Diancie

252 Atk Earth Plate Arceus-Ground Earthquake vs. 0 HP / 0 Def Mega Diancie: 342-404 (141.9 - 167.6%) -- guaranteed OHKO

(Diamond Storm boost) 252 Atk Earth Plate Arceus-Ground Earthquake vs. +1 0 HP / 0 Def Mega Diancie: 228-270 (94.6 - 112%) -- 68.8% chance to OHKO

TL;DR - Groundceus lives any 2 hits after SR damage and is able to outspeed to pick up an easy OHKO - thus allowing it to take even a critical hit etc. It has access to Recover to switch in for the entire battle, and this also makes M-Diancie set-up fodder for it.

 

[Didoy75]

reserving jirachi genesect

Genesect

Genesect @ Choice Scarf
Ability: Download
EVs: 252 Atk / 252 Spe / 4 Def
Hasty / Naive Nature
- Iron Head
- U-Turn
- Explosion
- Ice Beam

Hey, in my opinion, Genesect is one of the best Choice Scarf of the current metagame.
First, his ability Download is fantastic.
It is also able of gaining momentum thanks to STAB U-Turn that hits really hard many threats.
He also has a very large movepool.
I chose Ice Beam to OHKO Salamence and Rayquaza, which is always helpful.
Explosion is nice for killing (when you are low HP) pokes that resist your STAB like Ho-Oh and Groudon-Primal.

Against Mega-Diancie:

Genesect can come when Diancie uses CM or after Diancie kills something.
It can take one unboosted hit from Diancie if you misspredicted.
And destroy it.

Incredible Calc

+1 248 Atk Genesect Iron Head vs. 0 HP / 0 Def Diancie: 684-808 (283.8 - 335.2%) -- guaranteed OHKO

EDIT:
84 Atk Mega-Diancie Diamond Storm vs. 0 HP / 0- Def Genesect: 201-237 (71 - 83.7%) -- guaranteed 2HKO after Stealth Rock
Even if you are Hasty, you can take one hit and KO back.

 

[haxiom]

Will actually do this time, reserving Aegislash

 

[PoweredByRevenge]

I managed to get some time to do this today :]

Primal Kyogre: Check.

Kyogre @ Blue Orb
Ability: Drizzle
EVs: 248 HP / 248 Def / 12 Spe
Bold Nature
- Scald
- Ice Beam / Roar
- Rest
- Sleep Talk

Primal Kyogre is one of the best Mega Diancie checks out there. The EVs are for a standard defensive Pogre spread, this way it is able to take Diancie's Diamond storms better and with it's already high spdef stat it can take Moonblasts pretty easily too. Mega Diancie isn't able to 2hko Pogre even after rocks with any move, and Pogre can just Ohko MDiancie with Scald and Rest off the damage latter in the match.

Calcs (Stats are updated with ORAS changes):

Calcs

252 SpA Diancie Moonblast vs. 248 HP / 0 SpD Kyogre: 120-142 (29.7 - 35.2%) -- guaranteed 3HKO after Stealth Rock

80 Atk Diancie Diamond Storm vs. 248 HP / 248+ Def Kyogre: 133-157 (33 - 38.9%) -- guaranteed 3HKO after Stealth Rock

+1 252 SpA Diancie Moonblast vs. 248 HP / 0 SpD Kyogre: 180-213 (44.6 - 52.8%) -- guaranteed 2HKO after Stealth Rock

0 SpA Kyogre Scald vs. +1 0 HP / 0 SpD Diancie in Rain: 270-318 (112 - 131.9%) -- guaranteed OHKO

 

[DSM01]

Extreme Killer Arceus (offensive check)

Arceus @ Life Orb
EVs: 4 HP / 252 Atk / 252 Spe
Jolly Nature
- Swords Dance
- Extreme Speed
- Earthquake
- Stone Edge

While not a superb check, on offensive teams it can do the trick if you're in a bind. Arceus takes less than 50% from Moonblast and Diamond Storm while it outspeeds and OHKOes in return with EQ. EKiller can also force Diancie out if you bring it in after a kill. Stone Edge in the last slot can take out Lugia, defensive Yveltal, and Mence after SR.

252 Atk Life Orb Arceus Earthquake vs. 0 HP / 0 Def Diancie-Mega: 250-294 (103.7 - 121.9%)
252 SpA Diancie Moonblast vs. 4 HP / 0 SpD Arceus: 154-183 (40.8 - 48.1%)
80 Atk Diancie Diamond Storm vs. 4 HP / 0 Def Arceus: 147-174 (38.4 - 45.5%)

 

[Random Passerby]

Reserving Aegislash

Aegislash @ Leftovers
Ability: Stance Change
EVs: 252 HP / 4 Atk / 252 SpD
Sassy Nature
- King's Shield
- Toxic
- Gyro Ball
- Pursuit

Aegislash can come in on any move not named Earth Power and OHKO back with Gyro Ball. King's Shield is used to scout and gain for Leftovers recovery and stall for Toxic turns since this Aegislash is not invested in offense. Pursuit is used to trap Lati@s and Mega Gengar.

Calculations:
252 SpA Mega Diancie Earth Power vs. 252 HP / 252+ SpD Aegislash-Shield: 124-148 (38.2 - 45.6%) -- guaranteed 3HKO after Stealth Rock and Leftovers recovery
0 Atk Mega Diancie Diamond Storm vs. 252 HP / 0 Def Aegislash-Shield: 57-68 (17.5 - 20.9%) -- possible 6HKO after Stealth Rock and Leftovers recovery
4 Atk Aegislash-Blade Gyro Ball (73 BP) vs. 80 HP / 0 Def Mega Diancie: 412-492 (157.8 - 188.5%) -- guaranteed OHKO

EDIT: Didn't notice haxiom's reservation previously.

 

[haxiom]

Reserving Aegislash

Aegislash @ Leftovers
Ability: Stance Change
EVs: 252 HP / 4 Atk / 252 SpD
Sassy Nature
- King's Shield
- Toxic
- Gyro Ball
- Pursuit

Aegislash can come in on any move not named Earth Power and OHKO back with Gyro Ball. King's Shield is used to scout and gain for Leftovers recovery and stall for Toxic turns since this Aegislash is not invested in offense. Pursuit is used to trap Lati@s and Mega Gengar.

Calculations:
252 SpA Mega Diancie Earth Power vs. 252 HP / 252+ SpD Aegislash-Shield: 124-148 (38.2 - 45.6%) -- guaranteed 3HKO after Stealth Rock and Leftovers recovery
0 Atk Mega Diancie Diamond Storm vs. 252 HP / 0 Def Aegislash-Shield: 57-68 (17.5 - 20.9%) -- possible 6HKO after Stealth Rock and Leftovers recovery
4 Atk Aegislash-Blade Gyro Ball (73 BP) vs. 80 HP / 0 Def Mega Diancie: 412-492 (157.8 - 188.5%) -- guaranteed OHKO

I reserved that already :[

 

[Random Passerby]

I reserved that already :[

Sorry, didn't see it. Will do something else then.

 

[Iridiscent97]

Reserving water arceus

 

[Iridiscent97]

Nominating Arceus-Water, for it isn't half bad as a strong check and potential counter:

Arceus-Water @ Splash Plate
Ability: Multitype
EVs: 248 HP / 8 SpA / 252 Spe
Alternate EVs: 248 HP / 84 spD / 176 Spe
Timid Nature
- Calm Mind
- Judgement
- Recover
- Refresh / Ice Beam / Will-O-Wisp

Bulky water types fare pretty well against Mega Diancie. Unlike others such as Kyogre or Manaphy, however, Water Arceus has better mixed bulk, is faster than Diancie and above all has access to Recover. Water is also an amazing choice for a monotype Arceus form, as it has few weaknesses. Calm Mind is Water Arceus's best boosting move and is fairly easy to use in conjunction with the rest of the set; Water Arceus can switch into any of Mega Diancie's moves even at +1, following which it can proceed to start Recovering and setting up Calm Minds or straight up OHKO Diancie with Judgement:

Jewel vs Water-Donkey

• 252 SpA Mega Diancie Moonblast vs. 248 HP / 84 SpD Arceus-Water: 144-171 (32.5 - 38.6%) -- 98.7% chance to 3HKO
• 252 SpA Mega Diancie Earth Power vs. 248 HP / 84 SpD Arceus-Water: 98-116 (22.1 - 26.1%) -- 8.2% chance to 4HKO
• 4 Atk Mega Diancie Diamond Storm vs. 248 HP / 0 Def Arceus-Water: 139-165 (31.3 - 37.2%) -- 81.6% chance to 3HKO

• +1 252 SpA Mega Diancie Earth Power vs. 248 HP / 84 SpD Arceus-Water: 137-162 (30.9 - 36.5%) -- 65.6% chance to 3HKO
  
• +1 252 SpA Mega Diancie Moonblast vs. 248 HP / 84 SpD Arceus-Water: 217-256 (48.9 - 57.7%) -- 96.1% chance to 2HKO

Water-Donkey vs Jewel

• 0 SpA Splash Plate Arceus-Water Judgement vs. 0 HP / 0- SpD Mega Diancie: 308-366 (127.8 - 151.8%) -- guaranteed OHKO
• 0 SpA Splash Plate Arceus-Water Judgement vs. +1 0 HP / 0- SpD Mega Diancie: 206-246 (85.4 - 102%) -- 87.5% chance to OHKO after Stealth Rock

Water Arceus's set is pretty standard for the Calm Mind Arceus archetype: near-maximum HP is used to minimize hazard damage, while at least 176 Speed EVs with a Timid nature will outspeed base 110s such as Mega Diancie. Running the remaing 84 EVs in Special Defense allow it to take special hits better even without a boost, and will help it have the best odds of surviving two Moonblasts from a +1 Diancie if Water Arceus itself uses Calm Mind on the turn after it switches in. However, a maximum Speed set is also viable - it will in fact help Water Arceus stay competitive against other Arceus forms, at the cost of not being able to switch in on +1 Diancie so easily.

The moves are largely standard: Calm Mind is the preferred boosting move, while Recover is essential to stay alive. Judgement is the sole attacking move with no natural immunities, which makes Water Arceus a great candidate for a mono-attacking setup sweeper later in the game. The last move is up to choice: Refresh helps greatly against random Toxic or paralysis, while Will-O-Wisp grants utility against set-up sweepers such as Extreme Killer, Mega Salamence or SD Ground Arceus. Ice Beam can also be run in the last slot to complement Judgment nicely; it allows Water Arceus to nail the many Dragon types in Ubers, as well as prevent it from becoming an invitation for Primal Groudon, Ferrothorn and others.

Note: Swords Dance Water Arceus with an EV spread of 80 HP / 252 Atk / 176 Spe and with moves such as Swords Dance, Waterfall or Aqua Tail, Recover and Stone Edge, Ice Beam or similar coverage can also work well, being able to take any two hits from unboosted Mega Diancie and OHKOing back with its STAB. However, other forms of Arceus, such as Ground Arceus or Steel Arceus, generally do this better.

 

[SparksBlade]

Primal Groudon(Shaky Check)

Groudon @ Red Orb
Ability: Drought
EVs: 104 HP / 252 Atk / 96 SpD / 56 Spe
Adamant Nature
- Rock Polish
- Swords Dance
- Precipice Blades
- Stone Edge / Dragon Claw
This Primal Groudon can take any hit from a +0 Mega Diancie to set up a SD/RP depending on the requirement in the long run of the match, or outirhgt OHKO it if you don't miss. I didn't opt for the SpDef one cos it doesn't avoid the 2HKO anyway(11.7% chance on 252 HP / 252+ SpDef), and we can't guarantee 0 prior damage. So if you're taking a nice chunk of damage in a turn, i thought it best to utilize to that turn to really threaten the opp.

calcs

for the spdef pdon
252 SpA Mega Diancie Earth Power vs. 252 HP / 252+ SpD Primal Groudon: 178-210 (44 - 51.9%) -- 11.7% chance to 2HKO
252 SpA Mega Diancie Earth Power vs. 252 HP / 252+ SpD Primal Groudon: 178-210 (44 - 51.9%) -- guaranteed 2HKO after Stealth Rock
4 Atk Primal Groudon Precipice Blades vs. 0 HP / 0 Def Mega Diancie: 402-474 (166.8 - 196.6%) -- guaranteed OHKO

for the SD/RP pdon
252 SpA Mega Diancie Earth Power vs. 104 HP / 96 SpD Primal Groudon: 226-266 (61.5 - 72.4%) -- guaranteed 2HKO
252+ Atk Primal Groudon Precipice Blades vs. 0 HP / 0 Def Mega Diancie: 510-600 (211.6 - 248.9%) -- guaranteed OHKO

As is noticeable, Mega Diancie does nice damage in the 1 turn you set up, so it'd be wise if you pack a check to switch in repeatedly. Only send in PDon on a free switch, when the opposing team is slightly weakened/the checks to this set are gone.

DSM01 you should change that title to "Counter" because, from the OP

We are not looking for revenge killers, but for checks that are able to switch into the Pokemon in question at least once, and of course counters

edit: after talking to good users yohoE and WreckDra i understood the fault in this, so i'll elaborate according to what was explained to me.
[01:03] WreckDra: Checks range from revenge killer to where they can come in on some attacks at ceratian amounts of health and still beat the opposition 1 on one
[01:03] WreckDra: a counter
[01:04] WreckDra: is something that wins despite the conditions
So, as stated, it can only come in on a Moonblast at full health, and then it's a roll with Earth Power. Going by what WreckDra explained, i'm changing the title to "Check" rather than "Counter", and even then it's not a solid check at all. Most of the time, outside or an Arceus form, PDon is the only (frail) Mega Diancie check, so it should be used carefully when the opp has one.
What fooled me was the definition in the OP, which was later clarified by WreckDra.

 

[Iridiscent97]

This Primal Groudon can take any hit from a +0 Mega Diancie

Um, SparksBlade, I'm not sure how Primal Groudon can act as a counter or even a check to this Mega Diancie. As per your own calculations, and supported by these others, the only way Groudon can prevail over Diancie is if it is able to set up a Rock Polish, i.e., it already is at +2, it goes up against Diancie in a lead-lead situation, or it gets in at full health on Diancie as it sets up a Calm Mind. By my calculations, no way is Primal Groudon having any decent odds of living a combination of Moonblast or Diamond Storm and Earth Power as it tries to switch in and live the next turn (either to RP or to attack) since it will still be outsped by Diancie as it uses the Earth Power:

• 252 SpA Mega Diancie Moonblast vs. 104 HP / 96 SpD Primal Groudon: 89-105 (24.2 - 28.6%)
  
• 4 Atk Mega Diancie Diamond Storm vs. 104 HP / 0 Def Primal Groudon: 109-129 (29.7 - 35.1%)
  
• 252 SpA Mega Diancie Earth Power vs. 104 HP / 96 SpD Primal Groudon: 226-266 (61.5 - 72.4%)
• +1 252 SpA Mega Diancie Earth Power vs. 104 HP / 96 SpD Primal Groudon: 338-398 (92 - 108.4%) -- 50% chance to OHKO

Even in the best case scenario, Groudon will take 24.2% + 61.5% , i.e., 85.7% from Moonblast + Earth Power before it can retaliate. And these are for unboosted Diancie, with a full health Groudon, and without stealth rock on the field. In practice, this seems to me to be quite unlikely. As you yourself said, Only send in PDon on a free switch, but that makes it a very, very unreliable check at best, certainly not a good check or a counter. I might be missing something here, but then I would be especially grateful if you could clarify this for me.

 

[Dilwar]

Primal Groudon(Counter)

Groudon @ Red Orb
Ability: Drought
EVs: 104 HP / 252 Atk / 96 SpD / 56 Spe
Adamant Nature
- Rock Polish
- Swords Dance
- Precipice Blades
- Stone Edge / Dragon Claw
This Primal Groudon can take any hit from a +0 Mega Diancie to set up a SD/RP depending on the requirement in the long run of the match, or outirhgt OHKO it if you don't miss. I didn't opt for the SpDef one cos it doesn't avoid the 2HKO anyway(11.7% chance on 252 HP / 252+ SpDef), and we can't guarantee 0 prior damage. So if you're taking a nice chunk of damage in a turn, i thought it best to utilize to that turn to really threaten the opp.

calcs

for the spdef pdon
252 SpA Mega Diancie Earth Power vs. 252 HP / 252+ SpD Primal Groudon: 178-210 (44 - 51.9%) -- 11.7% chance to 2HKO
252 SpA Mega Diancie Earth Power vs. 252 HP / 252+ SpD Primal Groudon: 178-210 (44 - 51.9%) -- guaranteed 2HKO after Stealth Rock
4 Atk Primal Groudon Precipice Blades vs. 0 HP / 0 Def Mega Diancie: 402-474 (166.8 - 196.6%) -- guaranteed OHKO

for the SD/RP pdon
252 SpA Mega Diancie Earth Power vs. 104 HP / 96 SpD Primal Groudon: 226-266 (61.5 - 72.4%) -- guaranteed 2HKO
252+ Atk Primal Groudon Precipice Blades vs. 0 HP / 0 Def Mega Diancie: 510-600 (211.6 - 248.9%) -- guaranteed OHKO

As is noticeable, Mega Diancie does nice damage in the 1 turn you set up, so it'd be wise if you pack a check to switch in repeatedly. Only send in PDon on a free switch, when the opposing team is slightly weakened/the checks to this set are gone.

DSM01 you should change that title to "Counter" because, from the OP

Lol this is a check, a shaky one at best.

 

[SparksBlade]

lol how is it a Revenge Killer if it can ko after taking a hit? Using SD/RP is only an alternative that works if you predict well on that turn. Counters usually aren't supposed to take many hits as well, that's the job of checks.

I'm not sure how Primal Groudon can act as a counter or even a check to this Mega Diancie.

i never said it is a check, it is not supposed to be a check and can never be a check. It's a counter cos it can take a hit and ko back.

the only way Groudon can prevail over Diancie is if it is able to set up a Rock Polish, i.e., it already is at +2, it goes up against Diancie in a lead-lead situation, or it gets in at full health on Diancie as it sets up a Calm Mind. By my calculations, no way is Primal Groudon having any decent odds of living a combination of Moonblast or Diamond Storm and Earth Power as it tries to switch in and live the next turn (either to RP or to attack) since it will still be outsped by Diancie as it uses the Earth Power

it isn't supposed to take 2 hits from Mega Diancie at all. It's a counter. From the OP:

Pokémon A counters Pokémon B if Pokémon A can manually switch into Pokémon B and still win every time, even under the worst case scenario, without factoring in hax.

It comes in on a free switch, then it can ko Mega Diance, RP/SD just provide you alternatives if you're sure the opp will switch out.

The rest of your post also assumes that PDon is switching in on an attack, but it should not be.

Only send in PDon on a free switch

that makes it obv it can't take 2 hits. It can only take 1 predicted hit, so you have to use it with care. It's supposed to ko it when presented the opportunity, not take hits from it. Checks take repeated hits, not counters. Imo you're just confused b/w the definitions of checks and counters.

Lol this is a check, a shaky one at best.

i never said it is a check, so idk why assume it to be so

 

[haxiom]

lol how is it a Revenge Killer if it can ko after taking a hit? Using SD/RP is only an alternative that works if you predict well on that turn. Counters usually aren't supposed to take many hits as well, that's the job of checks.

i never said it is a check, it is not supposed to be a check and can never be a check. It's a counter cos it can take a hit and ko back.

it isn't supposed to take 2 hits from Mega Diancie at all. It's a counter. From the OP:

It comes in on a free switch, then it can ko Mega Diance, RP/SD just provide you alternatives if you're sure the opp will switch out.

The rest of your post also assumes that PDon is switching in on an attack, but it should not be.

that makes it obv it can't take 2 hits. It can only take 1 predicted hit, so you have to use it with care. It's supposed to ko it when presented the opportunity, not take hits from it. Checks take repeated hits, not counters. Imo you're just confused b/w the definitions of checks and counters.

You have it backwards. To be a check, you win 1v1 more or less, counters can MANUALLY switch in (read: not free switch).

 

[GnralLao]

Excadrill (Check)

Excadrill @ Air Baloon
Ability: Sand Rush
EVs: 4 HP / 252 Atk / 252 Spe
Adamant Nature
- Earthquake
- Iron Head
- Rock Slide
- Rapid Spin / Swords Dance

Provided that it's teamed up with TTar or HungryHungryHippo, Excadrill can come in on any of M-Diancie's moves (even at +2. If you feel lucky though, Exca also has a 50% chance of surviving a +3 Moonblast after SR) before outspeeding ang OHKOing back with the STAB move of choice.

Calcs:

80 Atk Diancie Diamond Storm vs. 4 HP / 0 Def Excadrill: 64-76 (17.6 - 20.9%) -- possible 5HKO after Stealth Rock
252 SpA Diancie Moonblast vs. 4 HP / 0 SpD Excadrill: 129-152 (35.6 - 41.9%) -- guaranteed 3HKO after Stealth Rock
+2 252 SpA Diancie Moonblast vs. 4 HP / 0 SpD Excadrill: 257-303 (70.9 - 83.7%) -- guaranteed 2HKO after Stealth Rock
252+ Atk Excadrill Earthquake vs. 0 HP / 0 Def Diancie: 338-402 (140.2 - 166.8%) -- guaranteed OHKO
252+ Atk Excadrill Iron Head vs. 0 HP / 0 Def Diancie: 544-648 (225.7 - 268.8%) -- guaranteed OHKO (sorry, don't know the code thingy to hide the calcs)

Without Air Baloon, Excadrill is completely helpless against M-Diancie's Earth Power to the point of being OHKOed by it. Therefore, it's the only item Exca should have if it wants to reliably check M-Diancie. Rock Slide is for Ho-Oh and stuff, Rapid Spin is for getting rid of those pesky entry hazards and SD is to increase its sweeping potential to dangrous levels.

 

[Dilwar]

lol how is it a Revenge Killer if it can ko after taking a hit? Using SD/RP is only an alternative that works if you predict well on that turn. Counters usually aren't supposed to take many hits as well, that's the job of checks.

i never said it is a check, it is not supposed to be a check and can never be a check. It's a counter cos it can take a hit and ko back.

it isn't supposed to take 2 hits from Mega Diancie at all. It's a counter. From the OP:

It comes in on a free switch, then it can ko Mega Diance, RP/SD just provide you alternatives if you're sure the opp will switch out.

The rest of your post also assumes that PDon is switching in on an attack, but it should not be.

that makes it obv it can't take 2 hits. It can only take 1 predicted hit, so you have to use it with care. It's supposed to ko it when presented the opportunity, not take hits from it. Checks take repeated hits, not counters. Imo you're just confused b/w the definitions of checks and counters.

i never said it is a check, so idk why assume it to be so

Read the definitions again please, properly.