Alright, so this here's a Gen 4 OU team, but I gladly managed to find an incredibly specific niche role for a NU pokemon :)
So to start my team out, I wanted to use a Machamp for his laughably enjoyable No Guard DynamicPunch. And built my team around it.
Machamp
244HP/252Atk/12Spe
No Guard
Adamant
@Lum Berry
DynamicPunch
Payback
Bullet Punch
Ice Punch
Pretty standard set with a pretty standard explanation. I'm using Ice Punch>Stone Edge primarily because the rest of my team has a tough time facing earthquakes, and so a Dragonite or Gliscor poses a real threat to most of my team. It does mean I can't hit Gyarados with more than a DynamicPunch on the switch, but hey, confusion is never bad.
Heatran
4HP/252SpA/252Spe
Timid
@Shuca Berry
Stealth Rock
Fire Blast
Explosion
Hidden Power Grass
HP Grass to take care of Swampert, another fairly basic set without much need for explanation I would think. Timid nature used to make sure an exploding Azelf doesn't take out my (BAN ME PLEASE) before the fun can get started :) Also helps serve to outspeed some mediocre speed poke's ranging around 70-86 (90 is just 1 too fast).
Tyranitar
4HP/252Atk/252Spe
Jolly
@Life Orb
Dragon Dance
Stone Edge
Crunch
Aqua Tail
Going the Aqua Tail route. As I said earlier, this team has a big weakness in ground type moves, like earthquake. Thus, being able to get Hippowdon, as well as other Tyranitar. Skarmory and Scizor can deal with my Heatran if they want to switch in, though it would be a shame to drop my Dragon Dance. Aqua Tail still hits for neutral damage on both, though Stone Edge hits Skarmory neutrally anyways with more power. Essentially, I'll have to watch for them and scout to make sure Tyranitar can be used effectively. Despite DDTar being used primarily as a sweeper, it's key with this team to try and get him out shortly after Machamp dies, to bring in sandstorm as soon as possible to help facilitate a sweep attempt later from either Tar or Empoleon.
Gliscor
252HP/4Def/252Spe
Sand Veil
Jolly
@Leftovers
Taunt
Earthquake
Roost
U-Turn
Taunt and U-Turn define my Gliscor. He's my physical wall, provides an incredibly important ground immunity, whilst also giving me a fighting resistance, and with a sandstorm up from Tyranitar, can hope for some evasions thanks to Sand Veil. The ability to U-Turn is definitely the most important aspect of my team though, as Gliscor will be using it quite often to force switches and help me set up.
Empoleon
8HP/252SpA/248Spe
Modest
@Life Orb
Agility
Ice Beam
Surf
Grass Knot
Another sweeper the team enjoys. With his littany of resistances, and one turn setup with Agility, Empoleon serves decently well as a backup sweeper. The key notion here is that with a stealth rock up from Heatran, and sandstorm kicking about from Tyranitar, Empoleon is well supported enough to avoid using a Petaya berry, freeing up the moveslot for ideal coverage.
Finally, the reason I really like this set. I'm always a fan of throwing in a weird pokemon that no one sees coming, but this niche was so incredibly specific I really enjoyed it.
Gardevoir
4HP/252SpA/252Spe
Trace
Timid
@Choice Scarf
Thunderbolt
Psychic
Trick
Focus Blast
Still not quite sure which to use in the last moveslot, but let me explain why I'm using Gardevoir at all.
When going through this team, I noticed a couple big problems. One, Infernape would tear through my team given the right conditions. My team is pretty slow as is, and the best counters to Infernape are Gliscor and Machamp (Heatran can also work, but he's got his plate full as is). Gliscor works pretty well, but I wanted a backup plan in case he fell early. Choice Scarfed Gardevoir comes in and hits hard with a STAB psychic, which ought to get rid of any Infernape problem I may be dealing with. But the second reason is I noticed my team is mincemeat before a DDGyarados that's gotten the turn to set up. Provided the Dos is carrying Earthquake, nothing really stands in it's way. Bring in Gardevoir. Most DDGyarados don't invest fully in speed as after a DD they'll be faster than most anything they're trying to sweep. This important subtlety is Gardevoir's key to success. Being just 1 point slower than Gyarados (translating to about 3 stats), it's important that the DDDos isn't fully invested in speed. Thanks to this, Gardevoir can come in after a poke dies and trace intimidate Gyarados, lowering it's attack. The choice scarf functions to deliver a thunderbolt before Gyarados even knows what hit it.
Finally, Gardevoirs serves two alternate purposes. With a beastly 125 SpA, she doesn't make a bad revenge killer at all. The choice of Focus Blast or Shadow Ball really comes down to who I need to take out. Focus Blast might be useful for Lucario, provided Lucario doesn't extremespeed (with a Swords Dance? No way Gardevoir is surviving that). Shadow Ball hits other psychic types and any ghosts lurking about (though a STAB psychic will probably do more damage to a Rotom than a Shadow Ball).
The second purpose is to provide the option of Tricking a choice scarf onto some unfortunate opponent, seriously reducing their capacity. Trick is always appreciated on any team.
So to start my team out, I wanted to use a Machamp for his laughably enjoyable No Guard DynamicPunch. And built my team around it.

Machamp
244HP/252Atk/12Spe
No Guard
Adamant
@Lum Berry
DynamicPunch
Payback
Bullet Punch
Ice Punch
Pretty standard set with a pretty standard explanation. I'm using Ice Punch>Stone Edge primarily because the rest of my team has a tough time facing earthquakes, and so a Dragonite or Gliscor poses a real threat to most of my team. It does mean I can't hit Gyarados with more than a DynamicPunch on the switch, but hey, confusion is never bad.

Heatran
4HP/252SpA/252Spe
Timid
@Shuca Berry
Stealth Rock
Fire Blast
Explosion
Hidden Power Grass
HP Grass to take care of Swampert, another fairly basic set without much need for explanation I would think. Timid nature used to make sure an exploding Azelf doesn't take out my (BAN ME PLEASE) before the fun can get started :) Also helps serve to outspeed some mediocre speed poke's ranging around 70-86 (90 is just 1 too fast).

Tyranitar
4HP/252Atk/252Spe
Jolly
@Life Orb
Dragon Dance
Stone Edge
Crunch
Aqua Tail
Going the Aqua Tail route. As I said earlier, this team has a big weakness in ground type moves, like earthquake. Thus, being able to get Hippowdon, as well as other Tyranitar. Skarmory and Scizor can deal with my Heatran if they want to switch in, though it would be a shame to drop my Dragon Dance. Aqua Tail still hits for neutral damage on both, though Stone Edge hits Skarmory neutrally anyways with more power. Essentially, I'll have to watch for them and scout to make sure Tyranitar can be used effectively. Despite DDTar being used primarily as a sweeper, it's key with this team to try and get him out shortly after Machamp dies, to bring in sandstorm as soon as possible to help facilitate a sweep attempt later from either Tar or Empoleon.

Gliscor
252HP/4Def/252Spe
Sand Veil
Jolly
@Leftovers
Taunt
Earthquake
Roost
U-Turn
Taunt and U-Turn define my Gliscor. He's my physical wall, provides an incredibly important ground immunity, whilst also giving me a fighting resistance, and with a sandstorm up from Tyranitar, can hope for some evasions thanks to Sand Veil. The ability to U-Turn is definitely the most important aspect of my team though, as Gliscor will be using it quite often to force switches and help me set up.

Empoleon
8HP/252SpA/248Spe
Modest
@Life Orb
Agility
Ice Beam
Surf
Grass Knot
Another sweeper the team enjoys. With his littany of resistances, and one turn setup with Agility, Empoleon serves decently well as a backup sweeper. The key notion here is that with a stealth rock up from Heatran, and sandstorm kicking about from Tyranitar, Empoleon is well supported enough to avoid using a Petaya berry, freeing up the moveslot for ideal coverage.
Finally, the reason I really like this set. I'm always a fan of throwing in a weird pokemon that no one sees coming, but this niche was so incredibly specific I really enjoyed it.

Gardevoir
4HP/252SpA/252Spe
Trace
Timid
@Choice Scarf
Thunderbolt
Psychic
Trick
Focus Blast
Still not quite sure which to use in the last moveslot, but let me explain why I'm using Gardevoir at all.
When going through this team, I noticed a couple big problems. One, Infernape would tear through my team given the right conditions. My team is pretty slow as is, and the best counters to Infernape are Gliscor and Machamp (Heatran can also work, but he's got his plate full as is). Gliscor works pretty well, but I wanted a backup plan in case he fell early. Choice Scarfed Gardevoir comes in and hits hard with a STAB psychic, which ought to get rid of any Infernape problem I may be dealing with. But the second reason is I noticed my team is mincemeat before a DDGyarados that's gotten the turn to set up. Provided the Dos is carrying Earthquake, nothing really stands in it's way. Bring in Gardevoir. Most DDGyarados don't invest fully in speed as after a DD they'll be faster than most anything they're trying to sweep. This important subtlety is Gardevoir's key to success. Being just 1 point slower than Gyarados (translating to about 3 stats), it's important that the DDDos isn't fully invested in speed. Thanks to this, Gardevoir can come in after a poke dies and trace intimidate Gyarados, lowering it's attack. The choice scarf functions to deliver a thunderbolt before Gyarados even knows what hit it.
Finally, Gardevoirs serves two alternate purposes. With a beastly 125 SpA, she doesn't make a bad revenge killer at all. The choice of Focus Blast or Shadow Ball really comes down to who I need to take out. Focus Blast might be useful for Lucario, provided Lucario doesn't extremespeed (with a Swords Dance? No way Gardevoir is surviving that). Shadow Ball hits other psychic types and any ghosts lurking about (though a STAB psychic will probably do more damage to a Rotom than a Shadow Ball).
The second purpose is to provide the option of Tricking a choice scarf onto some unfortunate opponent, seriously reducing their capacity. Trick is always appreciated on any team.