Rate my National Dex OU team

Question

Venusaur-Mega @ Venusaurite
Ability: Overgrow
EVs: 4 Def / 252 SpA / 252 SpD
Modest Nature
IVs: 0 Atk
- Leech Seed
- Protect
- Giga Drain
- Growth
my Wall Pokemon, i configure Leech Seed and use Growth in conjunction with the ninetales "Drough" skill, after the process I recover all my life with Giga drain

Ninetales @ Heat Rock
Ability: Drought
EVs: 252 SpA / 252 Spe
IVs: 0 Atk
- Flamethrower
- Energy Ball
- Nasty Plot
- Hypnosis
depending on who the enemy pokemon is, I use hypnosis and use "Nasty Plot" Flamethrower is my STAB and Energy Ball I use to defend myself from water type pokemons

Melmetal @ Leftovers
Ability: Iron Fist
EVs: 252 Atk / 164 SpD / 92 Spe
Adamant Nature
- Double Iron Bash
- Thunder Punch
- Earthquake
- Thunder Wave
the pokemon I use to defend myself from the fairy type at the beginning of the game and offer an advantage, I just set up Thunder wave to help the team in the future of the battle

Greninja @ Heavy-Duty Boots
Ability: Battle Bond
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Hydro Pump
- Dark Pulse
- Water Shuriken
- Ice Beam
greninja is my sweeper, I use Ice Beam to defend myself from fairy type pokemons, Dark Pulse and Water Shuriken are STAB's

Zapdos-Galar @ Heavy-Duty Boots
Ability: Defiant
EVs: 252 Atk / 252 Spe
Jolly Nature
- Thunderous Kick
- Brave Bird
- Close Combat
- Stomping Tantrum
I'm testing this pokemon, I have nothing to say about it

Kommo-o @ Dragonium Z
Ability: Bulletproof
EVs: 252 Def / 252 SpA
Timid Nature
- Clanging Scales
- Clangorous Soul
- Drain Punch
- Flamethrower
as soon as i put kommo-o (usually at the end of the game) i use his z-move to guarantee a buff, after that i just use the best move available

Comments

Your Venusaur doesn't have Chlorophyll, so it wouldn't get the speed boost from drought. I reccomend giving it Chlorophyll, removing Venusaurite, and using a different mega. I'd also give it Growth + Earth Power + Weather Ball. HDB Ash-Greninja is terrible,  it's extremely wanting for power. I wouldn't really use it on a sun team anyways, cause its Hydro Pump will be half power. I reccomend replacing it with something like Mega Garchomp. It checks Heatran decely, which your team is otherwise weak to. It gives you an immunity to Volt Switch as well.

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If you're using Kommo-o mainly late game as something of a finisher, I struggle to see what use you will get out of both its Z-move and Clangorous Soul. Flamethrower and Drain Punch also have a great deal of overlap on Kommo-o - both used as an answer to steel types such as Kartana, Magnezone and Ferrothorn, so you might be better off looking at going fully special with Flash Cannon over Drain Punch to deal with Faries and Boomburst over Clangorous Soul, or more physical with Poison Jab over Flamethrower for Faries, and Ice Punch over Clangorous Soul for Flying types. I also feel like you want Rest on Ninetales over Energy Ball to give you some recovery, given that you shouldn't have much trouble with water types once sun is up. Torkoal is also a more common sun setter.

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Don't run Kanto Ninetales in ND OU period. It's outclassed by Torkoal. Clangorous Soul can be run alongside the Z-Move bc it lets you setup multiple times.  The Z-Move is single use only. Give the Kommo-o more speeds evs instead of defense.  Replace DO with CC and Flame with boomburst.

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Most fairy moves are special/status and melmetal has less-than-average-for-a-legendary special defense

Answer 1

Well it's nice to see some Sun teams in Nat Dex, but I'd recommend some changes.

Venusaur :->

Ability: Overgrow ---> Chlorophyll
It is almost mandatory to have Chlorophyll ability in Sun Teams.

Item: Venusaurite ---> Life Orb
Use some other Mega Evolution, as Venusaur won't benefit from the Sun.

Move: Protect ---> Weather Ball
100 Base Power Fire Type move is gotta be a go to option IMO.

Ninetales :->

Pokemon: Ninetales ---> Torkoal
Torkoal is a better Sun Setter & Hazard Setter.

Greninja :->

Pokemon: Greninja ---> Mega Garchomp
Cdijk21 rightly stated that Greninja won't benefit from Sun. Use Mega Garchomp instead.

Kommo-O :->

Moveset: Can be much better
Well I don't have much to say, but you may refer to Blaziken Mask 85, his comment is really elaborated. Rest is your choice.

Comments

Mega Garchomp is perfect for this team, replace other mega evolution with that. I don't reccomend Solar Beam Venu, Giga Drain helps heal Life Orb recoil and also let's you have a grass STAB that works well in all weather.