I call this team "middle ground" because it is neither overly defensive nor overly offensive.
Special thanks to Phuquoph, Surgo, Jumpman, Hyra, Misty & DevilinDenial for all of your intelligent, insightful posts and your continued dedication to helping others improve. If you see a set of EVs or a moveset that seems familiar, please don't be offended; consider my opening paragraph the "opening credits," if you will.
I've been working on my team intermittenly and reading through countless posts in this forum; comparing myself to other teams and checking to make sure that I counter the top sweepers & Swampert, while making sure than I maintain an offensive pressure on the opponent. Hopefully my team can embody this. Here it is, a week's worth of work:
Swampert @ Leftovers
Torrent
Impish (-SA +Def)
240 HP, 56 Atk, 214 Def
-Stealth Rock
-Earthquake
-Ice Beam
-Stone Edge
I know I'm the millionth person to both use AND start with Pert, but I don't have many "starter-quality" guys on my team. Stealth Rock for kicks. The idea here is to cause major pain to Garch, Tyra, Sala and Gyara -- to say nothing of Metagross and whatever else needs a spanking. Swampert always has the weight of the world on his shoulders. . . . Always 2KOs all those guys without prior damage (can't ever OHKO without overhauling EVs, anyway), so he of course needs all the help he can get.
Heatran @ Choice Scarf
Flash Fire
Modest or Timid
50 HP, 208 or 252 SA, 252 or 208 Spd
-Flamethrower
-Dragon Pulse
-Explosion
-Flash Cannon/Hidden Power Grass
Can't switch straight into Tyra, but keeps it from sweeping in most cases. . . . Considering Overheat over Flamethrower, though without Modest I'm not sure it's worth it. A simply fantastic counter to Azelf, and backs up my team very well. Explosion, even with a -Atk Nature, because without any kind of recovery he can only switch in so many times. 399 Speed with Scarf, which is reasonable and allows him to scare Starmie & Dugtio. Starmie is a total bitch for this team, sadly. While Lustre Cannon is great against Tyranitar, Land Power still 2KOs, kills Electrics and other Heatran. Pert will want to switch into this guy 90% of the time. Salamence's Hydro Pump is scary here, but otherwise switches in, outspeeds and kills CG Sala.
EDIT: If I go with Flash Cannon, Timid. If I go with HPGrass, Modest. Lost Earth Power. Considering Phuquoph's RestTalk starter.
Gliscor @ Leftovers
Sand Veil
Impish (-SA +Def)
252 HP, 6 Atk, 252 Def
-Aerial Ace
-Knock Off
-Earthquake
-Roost
ADH's set. The new premier physical wall this gen. A perfect counter to Heracross. Enough to 2KO various other physical sweepers, such as: Tyra, Sala, Garch, et all, depending on the Fang. His Ice weakness ensures that he has to be played very carefully around things that may carry Hidden Power, such as Electivire/Infernape, though oddly he can take a Gyara Ice Fang. Hyper Cutter keeps his "teeth" in check, which I feel outweighs an Evasion boost. Unsure of which fang benefits my team more at this point; Pert and my next guy can take Gyarados on, so I'm thinking Ice. Has nothing on Swampert or Gyarados. Can take Crunches for a team that otherwise has Dark issues.
EDIT: Dropped Ice Fang for increased team synergy with either Knock Off or Somersault!
Knock Off is pure awesome and screws everything and anything just enough for the edge I need. With no additional speed investment, Gliscor will come off comfortably in the middle of "fast" and "slow," allowing for some fun comboing with Weavile or Heatran. Both seem viable, but ony one is responsible. Opting for both makes Gliscor more of a utilitarian liability than a defensive force.
EDIT 2: Changed to Sand Veil to coincide with the loss of Ice Fang. Knock Off is sexy.
Tangrowth @ Leftovers
Chlorophyll
Impish (-SA +Def)
240 HP, 192 Atk, 76 Def
-Sleep Powder
-Power Whip
-Earthquake
-Leech Seed
Can beat HP Grass Raikou. How quickly everyone forgot about this guy, but I never did. Sleep Powder gives it something to send to the bitches who wall his offensive. Leech Seed is love. Destroys Pert if it uses anything less than Ice Beam; beats Gyarados until it cries. Obviously, a lot resists Grass/Ground, but Leech Seed and Sleep Powder help incapacitate things he can't directly damage (like most Dragons, Skarm, a lot of Grass-types). Can't OHKO Tyra, but switches into CB max+ Crunches like nothing, but can be 2KOed by Stone Edge from the same Tyra due to Sand Stream. Can switch in on anything Rhyperior throws at it and outspeed for the OHKO, even Megahorn.
EDIT: Improved EVs
Weavile @ Choice Band
Pressure
Jolly (-SA +Spd)
6 HP, 252 Atk, 252 Spd
-Pursuit
-Ice Punch
-Night Slash
-Brick Break
Weavile doesn't switch in on anything but Ice & Psychic attacks; otherwise, it's a revenge killer or a late-game cleaner. I don't have much to say other than Pursuit is really cool, and I hope this does well. I needed something with decent speed and power, but everything else that's fast is pretty much weak to ice or offensively weak. So there you have it.
EDIT: Maximized potential.
Cresselia @ Leftovers
Levitate
Modest (-Atk +SA)
252 HP, 224 SA, 34 SD
-Ice Beam/Lunar Dance/Light Screen
-Grass Knot
-Psychic
-Moonlight
This was going to be a very special-defensive Uxie until I realized the only reason to use Uxie over Cresselia is Somersault, which I wasn't planning on using. This guy is just plain HARD to EV for. 266 SA to OHKO a bunch of friends, moderately good at sponging hits. Can't take a Salamence CG Meteor, but my Heatran can. Craps on Starmie, at least. Originally, I wanted Light Screen to help my team out, however I realised I'd have much more fun antagonizing Gengar and Infernape with Psychic. Won't help against a Heracross, though. Even more than Light Screen, I wish I had a spot for Crescent Dance. I could junk Ice Beam since I already have a lot of Dragon counters, but I dunno.
Explaination of EVs: Max HP, enough SA to OHKO just about whatever I need to with Grass Knot, Ice Beam and Psychic, rest in SD.
Threat Analysis Key:
great
just OK or situational
Tyranitar: Swampert, Tangrowth, Gliscor
Heracross: Gliscor, Heatran
Infernape: Cresselia, Heatran (depends)
Garchomp: Swampert, Gliscor, Cresselia
Electivire: Swampert, Gliscor, Tangrowth, Cresselia (depends)
Raikou: Tangrowth, Swampert, Gliscor
Starmie: Cresselia, Weaville
Gyarados: Swampert, Tangrowth
Azelf: Heatran, Weaville
Salamence: Swampert, Heatran, Cresselia, Gliscor
Heatran: Swampert, Heatran
Rhyperior: Tangrowth, Cresselia
Porygon-Z: Weaville, Heatran, Cresselia
Swampert: Tangrowth, Cresselia
And Weavile revenge kills anything but Ninjask, really. Okay, that's a bit of an overstatement, but still.
Obviously, I have issues with Boltbeamers. I may or may not be able to snuff opposing Electivire. I have no Haze or Phazer, so Baton Pass teams and sweepers that set up on me will probably. . . sweep.
Phew. After three long nights I'm satisfied enough to post it. Fire away, gentlemen!
Special thanks to Phuquoph, Surgo, Jumpman, Hyra, Misty & DevilinDenial for all of your intelligent, insightful posts and your continued dedication to helping others improve. If you see a set of EVs or a moveset that seems familiar, please don't be offended; consider my opening paragraph the "opening credits," if you will.
I've been working on my team intermittenly and reading through countless posts in this forum; comparing myself to other teams and checking to make sure that I counter the top sweepers & Swampert, while making sure than I maintain an offensive pressure on the opponent. Hopefully my team can embody this. Here it is, a week's worth of work:

Swampert @ Leftovers
Torrent
Impish (-SA +Def)
240 HP, 56 Atk, 214 Def
-Stealth Rock
-Earthquake
-Ice Beam
-Stone Edge
I know I'm the millionth person to both use AND start with Pert, but I don't have many "starter-quality" guys on my team. Stealth Rock for kicks. The idea here is to cause major pain to Garch, Tyra, Sala and Gyara -- to say nothing of Metagross and whatever else needs a spanking. Swampert always has the weight of the world on his shoulders. . . . Always 2KOs all those guys without prior damage (can't ever OHKO without overhauling EVs, anyway), so he of course needs all the help he can get.

Heatran @ Choice Scarf
Flash Fire
Modest or Timid
50 HP, 208 or 252 SA, 252 or 208 Spd
-Flamethrower
-Dragon Pulse
-Explosion
-Flash Cannon/Hidden Power Grass
Can't switch straight into Tyra, but keeps it from sweeping in most cases. . . . Considering Overheat over Flamethrower, though without Modest I'm not sure it's worth it. A simply fantastic counter to Azelf, and backs up my team very well. Explosion, even with a -Atk Nature, because without any kind of recovery he can only switch in so many times. 399 Speed with Scarf, which is reasonable and allows him to scare Starmie & Dugtio. Starmie is a total bitch for this team, sadly. While Lustre Cannon is great against Tyranitar, Land Power still 2KOs, kills Electrics and other Heatran. Pert will want to switch into this guy 90% of the time. Salamence's Hydro Pump is scary here, but otherwise switches in, outspeeds and kills CG Sala.
EDIT: If I go with Flash Cannon, Timid. If I go with HPGrass, Modest. Lost Earth Power. Considering Phuquoph's RestTalk starter.

Gliscor @ Leftovers
Sand Veil
Impish (-SA +Def)
252 HP, 6 Atk, 252 Def
-Aerial Ace
-Knock Off
-Earthquake
-Roost
ADH's set. The new premier physical wall this gen. A perfect counter to Heracross. Enough to 2KO various other physical sweepers, such as: Tyra, Sala, Garch, et all, depending on the Fang. His Ice weakness ensures that he has to be played very carefully around things that may carry Hidden Power, such as Electivire/Infernape, though oddly he can take a Gyara Ice Fang. Hyper Cutter keeps his "teeth" in check, which I feel outweighs an Evasion boost. Unsure of which fang benefits my team more at this point; Pert and my next guy can take Gyarados on, so I'm thinking Ice. Has nothing on Swampert or Gyarados. Can take Crunches for a team that otherwise has Dark issues.
EDIT: Dropped Ice Fang for increased team synergy with either Knock Off or Somersault!
Knock Off is pure awesome and screws everything and anything just enough for the edge I need. With no additional speed investment, Gliscor will come off comfortably in the middle of "fast" and "slow," allowing for some fun comboing with Weavile or Heatran. Both seem viable, but ony one is responsible. Opting for both makes Gliscor more of a utilitarian liability than a defensive force.
EDIT 2: Changed to Sand Veil to coincide with the loss of Ice Fang. Knock Off is sexy.

Tangrowth @ Leftovers
Chlorophyll
Impish (-SA +Def)
240 HP, 192 Atk, 76 Def
-Sleep Powder
-Power Whip
-Earthquake
-Leech Seed
Can beat HP Grass Raikou. How quickly everyone forgot about this guy, but I never did. Sleep Powder gives it something to send to the bitches who wall his offensive. Leech Seed is love. Destroys Pert if it uses anything less than Ice Beam; beats Gyarados until it cries. Obviously, a lot resists Grass/Ground, but Leech Seed and Sleep Powder help incapacitate things he can't directly damage (like most Dragons, Skarm, a lot of Grass-types). Can't OHKO Tyra, but switches into CB max+ Crunches like nothing, but can be 2KOed by Stone Edge from the same Tyra due to Sand Stream. Can switch in on anything Rhyperior throws at it and outspeed for the OHKO, even Megahorn.
EDIT: Improved EVs


Weavile @ Choice Band
Pressure
Jolly (-SA +Spd)
6 HP, 252 Atk, 252 Spd
-Pursuit
-Ice Punch
-Night Slash
-Brick Break
Weavile doesn't switch in on anything but Ice & Psychic attacks; otherwise, it's a revenge killer or a late-game cleaner. I don't have much to say other than Pursuit is really cool, and I hope this does well. I needed something with decent speed and power, but everything else that's fast is pretty much weak to ice or offensively weak. So there you have it.
EDIT: Maximized potential.

Cresselia @ Leftovers
Levitate
Modest (-Atk +SA)
252 HP, 224 SA, 34 SD
-Ice Beam/Lunar Dance/Light Screen
-Grass Knot
-Psychic
-Moonlight
This was going to be a very special-defensive Uxie until I realized the only reason to use Uxie over Cresselia is Somersault, which I wasn't planning on using. This guy is just plain HARD to EV for. 266 SA to OHKO a bunch of friends, moderately good at sponging hits. Can't take a Salamence CG Meteor, but my Heatran can. Craps on Starmie, at least. Originally, I wanted Light Screen to help my team out, however I realised I'd have much more fun antagonizing Gengar and Infernape with Psychic. Won't help against a Heracross, though. Even more than Light Screen, I wish I had a spot for Crescent Dance. I could junk Ice Beam since I already have a lot of Dragon counters, but I dunno.
Explaination of EVs: Max HP, enough SA to OHKO just about whatever I need to with Grass Knot, Ice Beam and Psychic, rest in SD.
Threat Analysis Key:
great
just OK or situational
Tyranitar: Swampert, Tangrowth, Gliscor
Heracross: Gliscor, Heatran
Infernape: Cresselia, Heatran (depends)
Garchomp: Swampert, Gliscor, Cresselia
Electivire: Swampert, Gliscor, Tangrowth, Cresselia (depends)
Raikou: Tangrowth, Swampert, Gliscor
Starmie: Cresselia, Weaville
Gyarados: Swampert, Tangrowth
Azelf: Heatran, Weaville
Salamence: Swampert, Heatran, Cresselia, Gliscor
Heatran: Swampert, Heatran
Rhyperior: Tangrowth, Cresselia
Porygon-Z: Weaville, Heatran, Cresselia
Swampert: Tangrowth, Cresselia
And Weavile revenge kills anything but Ninjask, really. Okay, that's a bit of an overstatement, but still.
Obviously, I have issues with Boltbeamers. I may or may not be able to snuff opposing Electivire. I have no Haze or Phazer, so Baton Pass teams and sweepers that set up on me will probably. . . sweep.
Phew. After three long nights I'm satisfied enough to post it. Fire away, gentlemen!