My first RMT.

OU team
Even though I'm a newbie here, you can be harsh in your criticism if you see fit. I probably need it. :)

Deoxys-D (Lead)
Item: Leftovers
Nature: Timid
Ability: Pressure
EVs: 252 HP/252 Speed/4 Def.
- Spikes
- Stealth Rock
- Taunt
- Night Shade

The increased speed on this thing has really been useful for surprise factor, as the quick taunt easily shuts down anyone trying to set up on this. If they switch as a result, I get a free layer of hazards. Night Shade for consistent damage.

Bisharp
Item: Leftovers
Nature: Adamant
Ability: Defiant
EVs: 140 HP/252 Attack/116 Speed
- Swords Dance
- Substitute
- Sucker Punch
- Brick Break

This set forces the opponent to predict. Either they set up on a predicted Sucker Punch or Swords Dance, or eat a Brick Break. Even unboosted, Brick Break does decent damage and comes with the added benefit of breaking screens. Bisharp also shares defensive synergy with Deoxys, in that Deoxys can take the Fighting type moves aimed at Bisharp, and Bisharp can take Dark and Ghost attacks meant for Deoxys.

Scizor
Item: Choice Band
Nature: Adamant
Ability: Technician
EVs: 252 Attack/252 HP/4 SpDef
- Bullet Punch
- U-Turn
- SuperPower
- Pursuit

Good revenge killer. This Scizor's Bullet Punch does good damage to most Pokes that don't resist it. Pursuit is mainly used to trap and kill Psychic-types, and is boosted by Technician. Baits fire type moves (along with Bisharp), potentially providing a free switch in for my Heatran.

Heatran
Item: Shuca Berry
Nature: Calm
Ability: Flash Fire
EVs: 244 HP/44 SpDef/220 Speed
- Lava Plume
- Toxic
- Protect
- Flash Cannon

The reason I don't use Air Balloon, is because I have never been in a situation where it worked. Most of the time I find myself switching to Heatran, the balloon gets popped and becomes useless. Hence, the shuca berry. As I stated before, Bisharp and Scizor help Heatran switch in, as they bait the fire type moves that Heatran can absorb.

Emolga
Item: Leftovers
Nature: Timid
Ability: Static
EVs: 160 HP/156 SpAtk/192 Speed
- Substitute
- Charge Beam
- Air Slash
- Roost

I know what you're thinking. Why would I use an NU Pokemon on an OU team? The answer: when this works, it's fun as hell. Heatran helps me get a free switch to Emolga; his 4x weakness to ground acts as good bait. I can then proceed to set up a substitute to see what the opponent does next. If I don't like it, I switch to the appropriate counter. If I do, Charge Beam everything. Air Slash covers ground and grass types, and Roost heals HP lost from substitute.

Nidoking
Item: Life Orb
Nature: Timid
Ability: Sheer Force (DW)
EVs: 252 SpAtk/4 HP/252 Speed
- Thunderbolt
- Ice Beam
- Flamethrower
- Earth Power

This set allows me to hit hard right off the bat. Thunderbolt and Ice Beam give me great coverage. Earth Power is for STAB. Flamethrower is mostly filler, but it has its uses against Pokes like Bronzong.

Something like Gastrodon or Swampert may give you a hard time, Whimsicott may also pose a threat. While Nidoking has great coverage, you still have a problem with bulkyGround/Water types. Heatran may carry HP Grass instead of Flash Cannon. Emolga's presence may be fun but it's going to be dead meat if it wouldn't work. There are a lot of Heatran baits out there that may possibly be better than Emolga.

I probably should replace Flash Cannon with HP Grass, seeing as how I don't have a single grass-type attack. I'm going to keep Emolga for now, because this team is new and I want to see how it does against a wide variety of teams. If it fails me more often than it works, I'll try a Skarmory and maybe relieve Deoxys-D of having to use Spikes. Granted, Whimsicott is a thorn in my side, but Nidoking and Scizor are capable of taking care of it. Thanks for the feedback.

If Scizor is holding Choice Band, make the EV spread 248 HP/252 Atk/8 Spe. That way, it takes less damage from Stealth Rock and lets it outspeed opposing Scizor who don't invest in Speed.

Bisharp is somewhat good in OU, but my main gripe about your current team is that half of it is Steel. Try out Scrafty instead; it's not as vulnerable to Fighting moves as Bisharp is:
-Dragon Dance
-Crunch
-Hi Jump Kick/Drain Punch
-Ice Punch/Drain Punch/Taunt
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Life Orb/Leftovers
Ability: Moxie

or
-Bulk Up
-Drain Punch
-Crunch/Dragon Tail
-Rest
Nature: Careful
EVs: 252 HP/8 Atk/248 SDef
Item: Leftovers
Ability: Shed Skin

If you want to keep Bisharp, that's fine, but you have to change the EV spread to 252 HP/252 Atk/4 Def; that way, it has an easier time taking hits.

If I find myself swapping Emolga for Scarmory (which is unlikely), I'll definitely drop Bisharp in favor of Scrafty. I like the look of that Dragon Dance set. I'll give it some thought nonetheless; I need something other than just Heatran to take fire attacks.

I noticed you are lacking a Water-type attacker.

Gastrodon is a nice one to try out. It can take hits well and has good Special stats.

Here's some sets you can use should you want to use it:

Sassy / Calm nature
Leftovers
Storm Drain
EVs: 252 HP, 4 Sp. Atk, 252 Speed
- Earthquake / Earth Power
- Scald / Ice Beam
- Toxic
- Recover

or try this...

Modest nature
Choice Specs
Storm Drain
EVs: 240 HP, 252 Sp. Atk, 16 Speed
- Surf
- Ice Beam
- Earth Power
- Recover / Hidden Power Grass

Hope you enjoy it!

Yes, something that has a Water typing would be good for your team. Heatran nor Nidoking would love one. You have a variety of choices like Gastrodon, Vaporeon, Swampert, Starmie, or Blastoise. The last two can also function as a Rapid Spinner if you do not like entry hazards. Starmie can also function as a killer with its good Speed and decent Special Attack. However, Starmie is TOO fragile so you might want a bulkier with less Speed.

Did anyone think to change Deoxys to speed form? Most of the times that I've seen him run as a lead with Rocks and everything, he's been in Speed rather than Defense. I don't know if it's really a better idea, but I figured I'd put it out there.

Not really, Deoxys-S is in Uber Tier.