Nihilego in OU

Question

Here is my team:
Nihilego @ Rockium Z
Ability: Beast Boost
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Power Gem
- Sludge Wave
- Thunderbolt
- Hidden Power [Ice]

Landorus-Therian @ Leftovers
Ability: Intimidate
EVs: 252 HP / 252 Def / 4 Spe
Impish Nature
- Earthquake
- Stone Edge
- Stealth Rock
- Knock Off

Rotom-Wash @ Leftovers
Ability: Levitate
EVs: 252 HP / 200 Def / 56 SpD
Bold Nature
IVs: 0 Atk
- Volt Switch
- Will-O-Wisp
- Hydro Pump
- Defog

Magearna @ Leftovers
Ability: Soul-Heart
EVs: 252 HP / 28 SpA / 228 SpD
Calm Nature
IVs: 0 Atk
- Fleur Cannon
- Pain Split
- Volt Switch
- Heart Swap

Greninja-Ash @ Choice Specs
Ability: Battle Bond
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Dark Pulse
- Water Shuriken
- U-turn
- Hydro Pump

Charizard-Mega-X @ Charizardite X
Ability: Tough Claws
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Earthquake
- Dragon Dance
- Flare Blitz
- Roost

Please help with any improvements. Thanks in advance.

Comments

If you're going to run Nihilego, have it play more of a role. Z-Move with four attacks is a very underwhelming strategy for OU. I would be using it as a hazard-setting lead (which could free a moveslot for Landorus), or with CS to pressure offensive Pokemon that could kill Charizard.
You're probably aware that Nihilego is a bad pick in OU, but it's worse when it doesn't complement your team, which I think is the case here. It doesn't hit much that will support a Charizard sweep, which isn't great considering how reliant this team is upon Charizard doing something in each game. You'd instantly improve this build by running Kartana in Nihilego's place.

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Thanks for your comment Fizz