K, so try not to be overly harsh if you can help it :]
Blastoise@Chesto Berry
252 HP/126 Def/129 Sp Def
Calm
Surf
Counter
Mirror Coat
Rest
Because nobody really expects a Blastoise. He holds up really well and can take at least two Thunderbolts/Energy Balls/Grass Knots from most special sweepers, same with Thunderpunches and fangs from physical sweepers. Counter and Mirror coat tend to really mess up offensive-minded Pokemon, especially those that get over-excited to see a plain, borderline water-type and think HEY, a couple of Thunderbolts and he's out of the way. Chesto-rest when his health gets low OR switch in and bring him back later with Cresselia's Lunar Dance. Also good bait for Electric attacks if I feel like giving Electivire a Motor Drive boost.
Electivire@Expert Belt
6 HP/252 Atk/252 Spd
Adamant
Thunderpunch
Ice punch
Cross Chop
Earthquake
Standard physical sweep. Not too hard to switch in with Blastoise as Electric bait.
Porygon-Z@Choice Specs/Life Orb
6 HP/252 Sp Atk/252 Spd
Modest
Tri-Attack
Thunderbolt
Ice Beam
Psychic
Tri-Attack is my primary move here. It's a pretty mean beast of an attack if Porygon-Z is fast enough to pull it off before he gets hurt or knocked out. The only issues Tri-Attack has are Ghosts or bulky Pokemon that are resistant to it, in which case Specs might put me in a bad position because I'll be forced to switch out under unpredictable conditions (Spikes, Stealth Rock, whatever). So I'm also contemplating Life Orb, but Porygon-Z can't take much more than two hits of anything before he's done for, which makes depleting his health risky. Suggestions?
Tyranitar@Choice Band
60 HP/252 Atk/196 Spd
Adamant
Earthquake
Stone Edge
Aerial Ace
Crunch
Another standard physical sweep. This ALMOST makes me want to set up a Trick Room scenario, just because he's out-sped by so many threats, such as Weavile and Heracross (but Trick Room might not be worth it for the rest of my team). In the event that I manage to out-speed the foe, Choice Band Tar does serious damage.
Cresselia@Custap Berry
252 HP/6 Sp Atk/ 252 Def
Calm
Thunderwave
Reflect
Ice Beam
Lunar Dance
Physical wall. Ice Beam is for Dragons. Custap Berry almost guarantees a chance to Lunar Dance when she's about to die, so I can bring back anything that I switched out on the brink of death, or Blastoise if I Rested after Chesto Berry had been used, if nothing else.
Spiritomb@Leftovers
252 HP/112 Def/144 SpD
Bold
Will-o-wisp
Hypnosis
Shadow Ball
Pain Split
A mix sort of wall. Will-o-wisp is for physical-minded Pokemon, and if used with Reflect cuts down physical damage to my team quite a bit. Hypnosis is for anything that's up to no good, or Heracross (which often ends up benefiting from Will-o-wisp, ironically). Spiritomb holds up well, and his terrible speed comes in handy when I want to use Pain Split after suffering a big blow the same turn.

Blastoise@Chesto Berry
252 HP/126 Def/129 Sp Def
Calm
Surf
Counter
Mirror Coat
Rest
Because nobody really expects a Blastoise. He holds up really well and can take at least two Thunderbolts/Energy Balls/Grass Knots from most special sweepers, same with Thunderpunches and fangs from physical sweepers. Counter and Mirror coat tend to really mess up offensive-minded Pokemon, especially those that get over-excited to see a plain, borderline water-type and think HEY, a couple of Thunderbolts and he's out of the way. Chesto-rest when his health gets low OR switch in and bring him back later with Cresselia's Lunar Dance. Also good bait for Electric attacks if I feel like giving Electivire a Motor Drive boost.

Electivire@Expert Belt
6 HP/252 Atk/252 Spd
Adamant
Thunderpunch
Ice punch
Cross Chop
Earthquake
Standard physical sweep. Not too hard to switch in with Blastoise as Electric bait.

Porygon-Z@Choice Specs/Life Orb
6 HP/252 Sp Atk/252 Spd
Modest
Tri-Attack
Thunderbolt
Ice Beam
Psychic
Tri-Attack is my primary move here. It's a pretty mean beast of an attack if Porygon-Z is fast enough to pull it off before he gets hurt or knocked out. The only issues Tri-Attack has are Ghosts or bulky Pokemon that are resistant to it, in which case Specs might put me in a bad position because I'll be forced to switch out under unpredictable conditions (Spikes, Stealth Rock, whatever). So I'm also contemplating Life Orb, but Porygon-Z can't take much more than two hits of anything before he's done for, which makes depleting his health risky. Suggestions?

Tyranitar@Choice Band
60 HP/252 Atk/196 Spd
Adamant
Earthquake
Stone Edge
Aerial Ace
Crunch
Another standard physical sweep. This ALMOST makes me want to set up a Trick Room scenario, just because he's out-sped by so many threats, such as Weavile and Heracross (but Trick Room might not be worth it for the rest of my team). In the event that I manage to out-speed the foe, Choice Band Tar does serious damage.

Cresselia@Custap Berry
252 HP/6 Sp Atk/ 252 Def
Calm
Thunderwave
Reflect
Ice Beam
Lunar Dance
Physical wall. Ice Beam is for Dragons. Custap Berry almost guarantees a chance to Lunar Dance when she's about to die, so I can bring back anything that I switched out on the brink of death, or Blastoise if I Rested after Chesto Berry had been used, if nothing else.

Spiritomb@Leftovers
252 HP/112 Def/144 SpD
Bold
Will-o-wisp
Hypnosis
Shadow Ball
Pain Split
A mix sort of wall. Will-o-wisp is for physical-minded Pokemon, and if used with Reflect cuts down physical damage to my team quite a bit. Hypnosis is for anything that's up to no good, or Heracross (which often ends up benefiting from Will-o-wisp, ironically). Spiritomb holds up well, and his terrible speed comes in handy when I want to use Pain Split after suffering a big blow the same turn.