Balanced Hackmon team?

Question

My team consists of:
Gengar-Mega @ Spooky Plate
Ability: Normalize
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Entrainment
- Toxic
- Judgment
- Sludge Bomb

Necrozma-Ultra @ Ultranecrozium Z
Ability: Contrary
EVs: 252 HP / 252 Atk / 252 Def / 252 SpA / 252 SpD / 252 Spe
Hasty Nature
- V-create
- Photon Geyser
- Leaf Storm
- Draco Meteor

Mewtwo-Mega-Y @ Wiki Berry
Ability: Adaptability
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Aura Sphere
- Psystrike
- Moongeist Beam
- Recover

Shedinja @ Lum Berry
Ability: Sturdy
Shiny: Yes
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Jolly Nature
- Endeavor
- Toxic
- Bullet Punch
- Magic Coat

Shedinja @ Lum Berry
Ability: Sturdy
EVs: 252 HP / 252 Def / 252 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Endeavor
- Toxic
- Recycle
- Magic Coat

Chansey @ Eviolite
Ability: Imposter
EVs: 252 HP / 252 Atk / 252 Def / 252 SpA / 252 SpD / 252 Spe
Relaxed Nature
- High Jump Kick
- Accelerock
- Acid Spray
- Transform
This Chansey doesn't need many moves, seeing as it'll be using other's moves

Comments

Why are you using TWO Sturdinjas???? No. Bad player. If one of your Shedinjas die, what makes you think almost an exact copy is going to be able to survive? Honestly, the meta has adapted way too much to Sturdinja for it to be even remotely good anymore. Any player worth their salt is going to see it, roll their eyes, and send in one of the many, many counters for it. if you're going to use Shedinja at all, use Magic Guard:

Shedinja @ Focus Sash
Ability: Magic Guard
EVs: everything
Jolly Nature
- Recycle
- Spiky Shield / Baneful Bunker
- x2 other troll moves

I haven't been keeping in touch with the hackmons meta for a while, but the fact that you have two Sturdinjas instead of one of these tells me that the meta hasn't realized that you can do this yet; I used it back when I played hackmons regularly, and would regularly catch people off-guard. At the very least, replace one of your Shedinjas with this, preferably replace one with this then replace the other with something else, like Prankster Topsy-Turvy, or Unaware Spectral Thief.

Answer 1

Gengar-Mega: Entrainment Set? Gengar Mega is fast so it's not hard to swap entrainment. Give it Anchor Shot or Spirit Shackle instead of Sludge bomb. Any Trapping moves like Infestation, bind, Clamp will work, too. Because When your opponent will switch out, the opposing pokemon will no longer has Entrainment. Recovering move is good too. You may use Recover instead of Toxic. It's just your choice. But Toxic is good for crippling your opponent.

Necrozma-Ultra: Mixed Contrary Set? It isn't the best idea. You should use either physical or special set.
Physical Contrary Necrozma
Necrozma-Ultra @ Ultranecrozium Z
Ability: Contrary
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Timid Nature
- V-create
- Photon Geyser
- Superpower
- Dragon Ascent
Special Contrary Necrozma
Necrozma-Ultra @ Ultranecrozium Z
Ability: Contrary
EVs: 252 HP / 252 SpA / 252 Def / 252 SpD / 252 Spe
Jolly Nature
- Draco Meteor
- Photon Geyser (Psycho Boost is good, too. So you may give Necrozma Psychium-A or Dragonium-Z)
- Overheat
- Fleur Cannon

But Prankstar Topsy-Turvy is really a problem. Dark type is immune to Prankstar T-T. So you may use Ash-Greninja with Fleur Cannon, Leaf Storm, Psycho boost and Overheat. Another problem is Spectral Thief. So you may use Lopunny-Mega, Regigigas or Slaking with the exact Physical Ultra- Necrozma set. Dark+Normal types (Alolan Rattata and Raticate) are immune to both T-T and Spectral Theif, but they are very weak.

Mewtwo-Mega-Y-: Adaptbility set? Then give it Safety Google's because Spore is common in Balanced Hackmons.

Shedinja and Shedinja : Sturdinja Sets? Then don't use Lum berry. Give them Focus Sash for surviving a Moongeist beam or Sunsteel Strike. Why Toxic? Use Foresight to hit ghosts. Remove Magic Guard for Safeguard. It protects you for five turns. Spore is good, too. But in Balanced Hackmons, usually only one pokemon has ability breaking moves like Sunsteel Strike. You will use Endeavor when the pokemon will use SS or MB to hit through Sturdy. And then use Bullet Punch to KO it. Extreme Speed is better than bullet punch. It has more priority. Use Jolly Nature. Give them 252 Atk and perfect 6 IVs.

Chansey: Use Fake Out/Soft-Boiled, Transform, Soak/Seismic Toss and Gastro Acid. Give it either Jolly or Calm nature.
And Spore set will work too. Then don't use Fake out/Sof...... . Use Spore, Nightmare, Knock off/Core Enforcer and Soft-Boiled.
Hope this helps.

Comments

Actually, mixed Contrary isn't that bad, but Contrary works best on a physical set because every move that lowers SpA just lowers SpA (with the exception of Clanging Scales), while there are plenty of Physical moves that lower multiple stats at once, allowing you to snowball Attack, Defenses, and Speed simultaneously.

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But most special attack reducing moves reduce the user's special attack by 2 stages, whereas attack reducing moves generally only reduces the user's attack by one stage, in addition with something else

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That is true, but I still think physical Contrary is better since, even though you're not snowballing damage as quickly, you're stacking speed and defenses, making you nigh unkillable. Special Contrary leaves you vulnerable to getting revenge-killed. Plus, it's not like you can't also stack damage as well, you'll just be doing it a bit slower.
You still have to watch out for Prankster Topsy-Turvy, which is why I'd recommend using a dark type for this. Good candidates are Mega TTar, Mega Gyarados, or, if you want something with more initial speed, Ash-Greninja. Dark-Arceus would be a great mon for this, except that Arceus doesn't actually change types unless it has Multitype and the corresponding plate/Z-Crystal.