I've been using this team for the past 2 days in shoddy to what I'd call success - it's easily been winning around 80% of my battles, and works well with good prediction.
V1.1
LEAD (purpose - set up rocks, surprise taunt or suicide leads, be the general nuisance he is)
Swampert @ Leftovers
Torrent, Impish, 100 HP/200 ATK/110 DEF/100 S.DEF
Stealth Rock
Stone Edge
Earthquake
Toxic
Yeah, it's Swampert. With the EV's given he's pleasantly bulky (survived a Mence Draco Meteor earlier, which may have been specced, I dunno). Basically, he's not going down on the first go unless it's against a predictable nape. Unfortunately you can't tell how skilled your opponent is at prediction, but I can generally guess from their pokemon what their first move is. If it looks like a taunter, EQ or Stone Edge. If it's a similar SRer, I'll set up my own too (unless I'm confident I can OHKO it).
Due to pert's bulkiness, he's likely to come back for an encore, so toxic takes up the final slot. Leftovers just enhances his wallingness.
SPINNER/SWEEPER (Purpose - Spinning and sweeping, oddly enough. Is nice and quick)
Starmie @ Choice Scarf (from petaya berrry)
Natural Cure, Modest (from timid), 6 HP/252 S.ATK/252 SPD
Trick (from Rapid Spin)
Thunderbolt (from Grass Knot)
Ice Beam
Surf (from Hydro Pump)
I'd say the set explains itself, but that's not very professional. The previous set had it's uses, but lacked the reliability you'd expect. The scarf is to beat any scarfnapes which may want a sweep, and to trick onto any walls (most effective on general crocunes, blisseys and cresselias). The rest is simple - Bolt-beam coverage with STAB surf to boot.
SWEEPER (Again, a nice nuisance as well)
Gyarados @ Lum Berry (from Life Orb)
Intimidate, Adamant, 110 HP/100 ATK/100 DEF/204 SPD
Aqua Tail
Dragon Dance
Ice Fang
Earthquake
A speedier BulkyGyara, I wanted something with a bit more 'oomf'. Not The speed EV's are a bit vague, but after 1 DD he's faster than base 120's in speed, so nice and quick. After the item change, it's greatly appreciated. Dusknoirs who may come in to burn, blisseys to toxic/paralyze, gengars to sleep, you name it - gyara shrugs them off with a 3HKO on every poke in OU after a DD and a good 2HKO at least on most. The EV's still work to absorb anything scizor throws at it, but may change for the sweeper set if need be.
STAR OF THE SHOW/SWEEPER (I love 'im)
Medicham @ Choice Scarf
Pure Power, Jolly, 38 HP/252 ATK/220 SPD
Hi Jump Kick
Ice Punch (From Fire Punch)
Thunderpunch
Psycho Cut
Nicely placed EV's put it where it needs to be with the boost - faster than Choice Scarf Timid Heatran, whom will be easily dealt with by the kick. The rest of the moves give excellent coverage, with his own bolt-beam. He'll deal with mences after the Attack cut too (at least with SR up, not sure about without). Psycho cut has got me some nice crits in the past too. Basically one of the best late-game sweepers IMO.
with trickzam out the way for a small while, here's the v1.1 addition
SMASHER (No tenderizing for this guy, he eats you whole)
Lucario @ Choice Band
Inner Focus, Jolly, 6 HP/252 ATK/252 SPD
Blaze Kick
Close Combat
Bullet Pawnch
Crunch
A little touch off the usual choice bander, but whereas that tragets flyers and such, my main worry is against darks and ghosts - and this beast counters them both beautifully.Blaze kick is meant for Bronzong and abomasnow, which the rest of the team doesn't do too well against. It was a swords dancer, but I found there was rarely time for something this frail to set up, despite his many resistances. Bullet punch is good for an in and out style of play, but I haven't used it that much at all - may swap for stone edge
REVENGE MAESTRO (He provides the G in REVENGE)
Gengar @ Focus Sash
Levitate, Timid, 6 HP/252 S.ATK/252 SPD
Destiny Bond
Counter
Shadow Ball
Thunderbolt
This set basically makes the most of Gnegar's unpredictability to make it the ultimate revnge set (for physical attackers, at least). Sandstorm sorta messes it up, but counter can still be used with good prediction. Shadow Ball and T-Bolt still provide good damage from that good s.atk,and my general strategy would generally go like this.
Arbitrary sweeper is on the loose, just killed one of my pokes
Gengar sent in
Gengar goes to sash territory after being hit, counters for the KO
new poke is sent in to revenge gengar or kill
with gengar's high speed, use Destiny bond, both die.
It has flaws against quicker pokes, but with either counter or Destiny Bond at least 1 poke is take out per battle, so it's efficient to say the least =).
PERFORMANCE
Swampert - good, but doesn't seem to do much compared to the other powerhouses in the team
Starmie - Missing thunderbolt can be a pain sometimes, but the ability to spin against teams who depend on entry hazards is invaluable. the petaya activates more often that expected against foes such as BP scizor,who can only 3HKO generally.
Gyarados - The intimidate is useful due to the influx of other Gyara recently, and lets him set up on scizors a lot. However, there isn't much other chance to set up
Medicham - Beooootiful, unless another scarfer comes along. Then he'll probably lose. But aside from that, absolute powerhouse.
Alakazam - either tricks or kills, always gets the job done.
Gengar - no-one predicts him correctly, it's beautiful. Just feels a bit weak sometimes.
General Threat list:
Ghost and Dark attacks - nothing in the team stops them, luckily they're kinda rare (Though I recently got swept by a timid Gengar).
Stat boosters - nothing really is quick enough to catch nijask before he starts up.
Multiple choice Scarfers - gggrrrr, shouldn't be allowed.
PREVIOUS MEMBERS
WALLBREAKER (Hey, he might be making a comeback)
Alakazam @ Choice Specs
Synchronize, Timid, 6 HP/252 S.ATK/252 SPD
Trick
Psychic
Signal Beam
Focus Blast
V1.1
LEAD (purpose - set up rocks, surprise taunt or suicide leads, be the general nuisance he is)

Swampert @ Leftovers
Torrent, Impish, 100 HP/200 ATK/110 DEF/100 S.DEF
Stealth Rock
Stone Edge
Earthquake
Toxic
Yeah, it's Swampert. With the EV's given he's pleasantly bulky (survived a Mence Draco Meteor earlier, which may have been specced, I dunno). Basically, he's not going down on the first go unless it's against a predictable nape. Unfortunately you can't tell how skilled your opponent is at prediction, but I can generally guess from their pokemon what their first move is. If it looks like a taunter, EQ or Stone Edge. If it's a similar SRer, I'll set up my own too (unless I'm confident I can OHKO it).
Due to pert's bulkiness, he's likely to come back for an encore, so toxic takes up the final slot. Leftovers just enhances his wallingness.

Starmie @ Choice Scarf (from petaya berrry)
Natural Cure, Modest (from timid), 6 HP/252 S.ATK/252 SPD
Trick (from Rapid Spin)
Thunderbolt (from Grass Knot)
Ice Beam
Surf (from Hydro Pump)
I'd say the set explains itself, but that's not very professional. The previous set had it's uses, but lacked the reliability you'd expect. The scarf is to beat any scarfnapes which may want a sweep, and to trick onto any walls (most effective on general crocunes, blisseys and cresselias). The rest is simple - Bolt-beam coverage with STAB surf to boot.
SWEEPER (Again, a nice nuisance as well)

Gyarados @ Lum Berry (from Life Orb)
Intimidate, Adamant, 110 HP/100 ATK/100 DEF/204 SPD
Aqua Tail
Dragon Dance
Ice Fang
Earthquake
A speedier BulkyGyara, I wanted something with a bit more 'oomf'. Not The speed EV's are a bit vague, but after 1 DD he's faster than base 120's in speed, so nice and quick. After the item change, it's greatly appreciated. Dusknoirs who may come in to burn, blisseys to toxic/paralyze, gengars to sleep, you name it - gyara shrugs them off with a 3HKO on every poke in OU after a DD and a good 2HKO at least on most. The EV's still work to absorb anything scizor throws at it, but may change for the sweeper set if need be.
STAR OF THE SHOW/SWEEPER (I love 'im)

Medicham @ Choice Scarf
Pure Power, Jolly, 38 HP/252 ATK/220 SPD
Hi Jump Kick
Ice Punch (From Fire Punch)
Thunderpunch
Psycho Cut
Nicely placed EV's put it where it needs to be with the boost - faster than Choice Scarf Timid Heatran, whom will be easily dealt with by the kick. The rest of the moves give excellent coverage, with his own bolt-beam. He'll deal with mences after the Attack cut too (at least with SR up, not sure about without). Psycho cut has got me some nice crits in the past too. Basically one of the best late-game sweepers IMO.
with trickzam out the way for a small while, here's the v1.1 addition
SMASHER (No tenderizing for this guy, he eats you whole)

Lucario @ Choice Band
Inner Focus, Jolly, 6 HP/252 ATK/252 SPD
Blaze Kick
Close Combat
Bullet Pawnch
Crunch
A little touch off the usual choice bander, but whereas that tragets flyers and such, my main worry is against darks and ghosts - and this beast counters them both beautifully.Blaze kick is meant for Bronzong and abomasnow, which the rest of the team doesn't do too well against. It was a swords dancer, but I found there was rarely time for something this frail to set up, despite his many resistances. Bullet punch is good for an in and out style of play, but I haven't used it that much at all - may swap for stone edge
REVENGE MAESTRO (He provides the G in REVENGE)

Gengar @ Focus Sash
Levitate, Timid, 6 HP/252 S.ATK/252 SPD
Destiny Bond
Counter
Shadow Ball
Thunderbolt
This set basically makes the most of Gnegar's unpredictability to make it the ultimate revnge set (for physical attackers, at least). Sandstorm sorta messes it up, but counter can still be used with good prediction. Shadow Ball and T-Bolt still provide good damage from that good s.atk,and my general strategy would generally go like this.
Arbitrary sweeper is on the loose, just killed one of my pokes
Gengar sent in
Gengar goes to sash territory after being hit, counters for the KO
new poke is sent in to revenge gengar or kill
with gengar's high speed, use Destiny bond, both die.
It has flaws against quicker pokes, but with either counter or Destiny Bond at least 1 poke is take out per battle, so it's efficient to say the least =).
PERFORMANCE
Swampert - good, but doesn't seem to do much compared to the other powerhouses in the team
Starmie - Missing thunderbolt can be a pain sometimes, but the ability to spin against teams who depend on entry hazards is invaluable. the petaya activates more often that expected against foes such as BP scizor,who can only 3HKO generally.
Gyarados - The intimidate is useful due to the influx of other Gyara recently, and lets him set up on scizors a lot. However, there isn't much other chance to set up
Medicham - Beooootiful, unless another scarfer comes along. Then he'll probably lose. But aside from that, absolute powerhouse.
Alakazam - either tricks or kills, always gets the job done.
Gengar - no-one predicts him correctly, it's beautiful. Just feels a bit weak sometimes.
General Threat list:
Ghost and Dark attacks - nothing in the team stops them, luckily they're kinda rare (Though I recently got swept by a timid Gengar).
Stat boosters - nothing really is quick enough to catch nijask before he starts up.
Multiple choice Scarfers - gggrrrr, shouldn't be allowed.
PREVIOUS MEMBERS
WALLBREAKER (Hey, he might be making a comeback)

Alakazam @ Choice Specs
Synchronize, Timid, 6 HP/252 S.ATK/252 SPD
Trick
Psychic
Signal Beam
Focus Blast