This team, at first glance, looks like it will underperform in OU because most of your choices are quite questionable as OU Pokémon. However, I have good news for you: We can turn this into a great UU team with a few tweaks. For this, Dragonite must be replaced by another Dragon-type that's in a lower tier, and what screams amazing in UU other than Hydreigon?
Meganium
In general, I advocate against offensive Meganium. It is quite slow and not bulky enough to be a tank, but neither offensive enough to be described as a slow sweeper. A more sensible choice would be Roserade.
Roserade @ Life Orb
Ability: Natural Cure
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Giga Drain
- Sludge Bomb
- Leaf Storm
- Hidden Power Fire
Alternatively, should you want to stay Physical, you could opt for Chesnaught but this would make you weaker to Fairy-type:
Chesnaught @ Leftovers
Ability: Bulletproof
EVs: 252 HP / 252 Def / 4 SpD
Impish Nature
- Spikes
- Leech Seed
- Spiky Shield
- Drain Punch
This is a defensive moveset that allows you to set down spikes and play defensively. Leech Seed and Leftovers offer reliable recovery so he stays healthy throughout the game; Spiky Shield, his signature move, is a protection that damages physical attackers. Very handy. If the mindgames are a little complicated for you yet, go for a more offensive build:
Chesnaught @ Assault Vest
Ability: Bulletproof
EVs: 240 HP / 252 Atk / 16 SpD
Adamant Nature
- Wood Hammer
- Stone Edge
- Earthquake
- Drain Punch
Arcanine
This seems a little off. Arcanine has amazing potential and a great movepool you're not utlizing to the fullest, so try this instead:
Arcanine @ Life Orb / Expert Belt
Ability: Flash Fire
EVs: 252 Atk / 252 Spe / 4 SpD
Jolly Nature
-Flare Blitz
-Morning Sun / Extreme Speed
-Close Combat
-Wild Charge
Wild Charge is useful against Water-type Pokémon. If you're not into it, though, solid alternatives include Crunch and Outrage when you have eliminated Fairy-type Pokémon. Italic choices go together and present a more offensive but less sustainable version.
Lapras
I'll say it's fine. I do have a better version but this Lapras of yours is okay, especially for a newbie at Pokémon.
Lapras @ Choice Specs
Ability: Water Absorb
EVs: 120 HP / 252 SpA / 136 Spe
Modest Nature
- Freeze-Dry
- Ice Beam
- Hydro Pump
- Surf
Electivire
Adamant nature and Thunderbolt do not go well together. Also, Flash is unreliable because Accuracy can prove to be very much luck-based. For this, replace the two moves with Ice Punch and Cross Chop.
Snorlax
Snorlax @ Leftovers
Ability: Thick Fat
EVs: 188 HP / 144 Def / 176 SpD
Careful Nature
- Curse
- Body Slam
- Rest
- Sleep Talk
This is by excellence Snorlax' defaut, bread-and-butter moveset. You're missing a lot of what he has to offer if you run something else to be honest. I don't like Snorlax but I respect his strengths. You really need to use Curse two to three times at most then you can spam Body Slam once you got rid of the Ghost-types. If you're low on HP, Rest and Sleep Talk can make you keep going for as long as possible.
Finally, Hydreigon:
Hydreigon @ Choice Scarf
Ability: Levitate
EVs: 252 SpA / 252 Spe / 4 Atk
Hasty Nature
-U-Turn
-Superpower
-Draco Meteor
-Dark Pulse
Quite straightforward. Your special attacks are stronger, but Superpower can be amazing against Steel-, Rock- and Normal-types, as well as Dark- and Ice-types. U-Turn is interesting against Grass- and Dark-types.
That's it!
