You forgot to include leftovers in your calc btw
Reuniclus @ Leftovers
Ability: Magic Guard
EVs: 252 HP / 252 Def / 4 SpA
Bold Nature
IVs: 0 Atk
- Calm Mind
- Recover
- Psyshock
- Focus Blast
You switch in and set up. Ez game
252 Atk Pure Power Medicham-Mega High Jump Kick vs. 252 HP / 252+ Def Reuniclus: 153-180 (36 - 42.4%) -- guaranteed 3HKO
well I proved it is walled without lefties so imagine if using lefties!
Well it does learn Rock Slide that could be decent but for the set above M-Medi can't touch Shed without sand support
Shedinja @ Heavy-Duty Boots
Ability: Wonder Guard
EVs: 252 SpA or 252 Atk / 252 Spe
IVs: 0 Atk or 0 SpA / 0 Def / 0 SpD
Mild/Lonely Nature
- Toxic
- Will-O-Wisp
- Hex/X-Scissor
- Protect
M-Medi is a mon that can be pretty scary for
stall. Mega-Sableye has to risk getting a para/freeze and gets 3HKOed.
So Shedinja is the COUNTER of choice.
M-Medi will never have something to hit Shedinja on a surious Set.
You have to watch out for Dark types like gren or Weavile but you can OHKO them with
X-Scissor and 168+ Atk Investment.
Because of Ditto all the Def Stats should be as low as possible.
I hope nobody reserved Shedinja.
Rock Slide isn't worth the moveslot,
Reuniclus @ Leftovers
Ability: Magic Guard
EVs: 252 HP / 252 Def / 4 SpA
Bold Nature
IVs: 0 Atk
- Calm Mind
- Recover
- Psyshock
- Focus Blast
You switch in and set up. Ez game
252 Atk Pure Power Medicham-Mega High Jump Kick vs. 252 HP / 252+ Def Reuniclus: 153-180 (36 - 42.4%) -- guaranteed 3HKO
Counters
Shedinja @ Heavy-Duty Boots
Ability: Wonder Guard
EVs: 252 SpA or 252 Atk / 252 Spe
IVs: 0 Atk or 0 SpA / 0 Def / 0 SpD
Mild/Lonely Nature
- Toxic
- Will-O-Wisp
- Hex/X-Scissor
- Protect
M-Medi is a mon that can be pretty scary for
stall. Mega-Sableye has to risk getting a para/freeze and gets 3HKOed.
So Shedinja is the COUNTER of choice.
M-Medi will never have something to hit Shedinja on a surious Set.
You have to watch out for Dark types like gren or Weavile but you can OHKO them with
X-Scissor and 168+ Atk Investment.
Because of Ditto all the Def Stats should be as low as possible.
I hope nobody reserved Shedinja.
Reserving Deoxys-Defense
Counter: Deoxys-Defense
/
Deoxys-Defense @ Leftovers / Rocky Helmet
Ability: Pressure
EVs: 252 HP / 4 Def / 252 Spe
Impish Nature
IVs: 0 Atk
- Spikes
- Taunt
- Recover
- Knock Off / Seismic Toss
This alien is one of the best counters to mega medicham as the pure psychic typing allows it to resist the dual STAB of mega medicham while not crumbling to any of it's coverage, in this case thunder punch. You pretty much only fear a thunder punch para hax or good double switches by mega medicham with stealth rocks up. You can opt for rocky helmet to wear down mega medicham or other physical attackers quickly if you are confident that you aren't gonna get outplayed too much, otherwise leftovers is better while providing passive recovery that helps to deal with other threats that aren't making contact while slightly reducing the need to constantly recover against mega medicham in the long run.
252 Atk Pure Power Medicham-Mega High Jump Kick vs. 252 HP / 4+ Def Deoxys-Defense: 106-126 (34.8 - 41.4%) -- guaranteed 3HKO after Stealth Rock and Leftovers recovery
252 Atk Pure Power Medicham-Mega High Jump Kick vs. 252 HP / 4+ Def Deoxys-Defense: 106-126 (34.8 - 41.4%) -- guaranteed 3HKO after Stealth Rock
G L A C I A TTTTTEEEE
Altaria-Mega @ Altarianite
Ability: Pixilate
EVs: 252 HP / 108 Def / 148 SpD
Relaxed Nature
- Pursuit
- Roost
- Hyper Voice
- Haze
Yo listen, this set slaps so hard trust me. It walls any decent Victini set. Altaria has a great typing and is bulky enough to wall Banded Victini avoiding 2HKO.
252 Atk Choice Band Victini V-create vs. 252 HP / 108+ Def Altaria-Mega: 139-164 (39.2 - 46.3%) -- guaranteed 3HKO
Moreover, it can take on Z-Celebrate Victini even after rocks damage (you must have Mega Evolved before)
+1 252 SpA Victini Stored Power (120 BP) vs. 252 HP / 148 SpD Altaria-Mega: 204-241 (57.6 - 68%) -- guaranteed 2HKO
Possible damage amounts: (204, 207, 210, 211, 214, 216, 219, 222, 223, 226, 228, 231, 234, 235, 238, 241)
Here you use Haze and endure Searing Shot.
252 SpA Victini Searing Shot vs. 252 HP / 148 SpD Altaria-Mega: 57-67 (16.1 - 18.9%) -- possible 6HKO
Possible damage amounts: (57, 57, 58, 59, 60, 60, 60, 61, 62, 63, 63, 64, 65, 66, 66, 67)
241+67=308. Altaria after Stealth Rock is at 310 HP. Survives and Roosts.
Furthermore, Altaria can act as Trick absorber for Choice Band sets. Pursuit here takes advantage of a Hazed or Choice-Locked Victini.
0 Atk Altaria-Mega switching boosted Pursuit (80 BP) vs. -1 0 HP / 0 Def Victini: 188-222 (55.1 - 65.1%) -- guaranteed 2HKO
Edit: I chose Altaria as it can easily receive Glaciate.
Gastrodon @ Leftovers counter
Ability: Storm Drain
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Recover
- Scald
- Earth Power/Earthquake
- Toxic
252 SpA Victini Psychic vs. 252 HP / 4 SpD Gastrodon: 144-171 (33.8 - 40.1%) -- guaranteed 3HKO
the calc above is the hardest hit victini viable sets could do to gastrodon, gastro could switch in and then recover, the only thing victini could do is toxic gastro but gastro could switch to heatran or smth else that absorbs toxic and doesn't die to vic stabs
Heatran @ Leftovers
Ability: Flash Fire
EVs: 252 HP / 132 SpD / 124 Spe
Calm Nature
IVs: 0 Atk
- Lava Plume
- Earth Power
- Toxic
- Stealth Rock
Check: Garchomp
Garchomp @ Choice Scarf
Ability: Rough Skin
EVs: 252 Atk / 4 SpA / 252 Spe
Hasty Nature
- Earthquake
- Stone Edge
- Fire Blast
- Poison Jab
Yea that's right this beat every victini set possible with just one set.which sounds like a crime. However every sane person will not use it as this is a bad form of speed control and sacrifices tons of breaking power and ability to set up stealth rock but i'm paranoid about not beating other sets
Choice band
252 Atk Choice Band Victini V-create vs. 0 HP / 0- Def Garchomp: 213-251 (59.6 - 70.3%) -- guaranteed 2HKO
252 Atk Garchomp Earthquake vs. 0 HP / 0 Def Victini: 326-386 (95.6 - 113.1%) -- 75% chance to OHKO
We are faster so we will land the faster earthquake, not that the opponent will usually stay in anyways...
Utility
Notes: 140HP / 252 SpA / 116 Spe Modest Nature is the spread
252+ SpA Victini Glaciate vs. 0 HP / 0 SpD Garchomp: 296-352 (82.9 - 98.5%) -- 31.3% chance to OHKO after Stealth Rock
252 Atk Garchomp Earthquake vs. 140 HP / 0 Def Victini: 326-386 (86.7 - 102.6%) -- 18.8% chance to OHKO
We are faster and we will land the faster earthquake too. Glaciate speed drop won't stop us from outspeeding it, giving the victini a nasty surprise. Stealth rock is also needed for victini to even have a chance to OHKO garchomp, not that this variant of victini usually want to stay in on garchomp but you get the point.
Choice Scarf
252 Atk Victini V-create vs. 0 HP / 0- Def Garchomp: 142-168 (39.7 - 47%) -- guaranteed 3HKO
252 Atk Garchomp Earthquake vs. 0 HP / 0 Def Victini: 326-386 (95.6 - 113.1%) -- 75% chance to OHKO
Again we have the higher speed, and it's especially brutal considering that most victini will click the assumed faster u-turn for potentially abusable chip damage just to watch in horror as the mythical mon is heavily damaged if not outright koed. Heck you could even switch in on the expected trick and you practically got a free switch.
Z-Celebrate
+1 252 SpA Victini Stored Power (120 BP) vs. 0 HP / 0 SpD Garchomp: 280-331 (78.4 - 92.7%) -- guaranteed 2HKO
252 Atk Garchomp Earthquake vs. +1 0 HP / 0 Def Victini: 218-260 (63.9 - 76.2%) -- guaranteed 2HKO
Now this is the reason why i went for this scarf set. It was painful trying to counter this set with the other candidates i thought of while dealing fairly well against the other sets. Due to garchomp's trolling base 100s' speed it can outspeed +1 victini with a scarf and earthquake the victini away while surviving a stored power after stealth rock chip.
/ Heavy-Duty Boots -> 
-> 
haze alt goat wtf
