I wanted to squeeze this in before 4th Gen is completely forgotten. While the traditional MixPert has been one of my favorite leads in the past, it doesn't quite live up to its name as a mixed attacker with almost 0 investment. I decided to take a more offensive approach to Swampert to take care of its excellent movepool and type coverage. The results have turned out surprisingly well, as with the proper support, this Swampert acts as a good hole-puncher while remaining physically bulky.
Topic Title: Offensive Mixed Attacker
http://www.smogon.com/dp/pokemon/swampert
[set]
name: MixPert (Offensive)
-Earthquake
-Stone Edge
-Avalanche/Waterfall
-Surf/Ice Beam
item: Leftovers
nature: Brave/Quiet
evs: 44 HP / 252 Atk / 128 Def / 84 SpA
Why this set deserves to be on site:
-Offers strong attacks from both ends of the spectrum.
-Very good physical bulk - can switch into Dragon Dance Gyarados and Dragonite who have taken Stealth Rock Damage, take the hit, and OHKO both most of the time with Stone Edge or Ice Beam, respectively.
-Catches many opponents off guard, expecting a Curse or Support set; completely avoids being taunt bait.
-Excellent offensive coverage with EdgeQuake, Ice, and potentially Water.
Additional Comments:
-Expert Belt can be used to bolster its awesome type coverage, but you lose vital recovery.
-44/128 physical defense allows it to take boosted STAB from Gyarados and Dragonite (though Gyarados' Waterfall will leave you at a minimum of 15%)
Teammates and Counters:
-Swampert absolutely hates Toxic Spikes or Toxic. Tentacruel can be used to absorb Toxic Spikes and clear Stealth Rock and Spikes from the field, and leave Toxic Spikes of his own.
-As mentioned before, Stealth Rock is absolutely essential to getting specific kills on Dragonite and Gyarados, and only aid Swampert's attacks on different opponents.
-By virtue of being so slow, this set is not meant to sweep by any means. It helps punch holes in your opponents for other members of your team to pick off.
-Rotom-w can block Rapid Spin and put a hold on Heatran, who mostly pack Hidden Power Grass which demolishes Swampert.
-Traditional scouts like Choice Band Scizor help absorb a predicted Toxic from Blissey, and make a powerful exit with U-Turn.
-Toxic Spikes are literally thorns in Swampert's side, and Leftovers and lack of recovery don't compensate for this.
-Bulky grass types such as Shaymin and Celebi are a huge problem. You have no business trying to hit them with Ice Beam, but if you pack Avalanche and predict correctly, you can hit them on the switch
Topic Title: Offensive Mixed Attacker

http://www.smogon.com/dp/pokemon/swampert
[set]
name: MixPert (Offensive)
-Earthquake
-Stone Edge
-Avalanche/Waterfall
-Surf/Ice Beam
item: Leftovers
nature: Brave/Quiet
evs: 44 HP / 252 Atk / 128 Def / 84 SpA
Why this set deserves to be on site:
-Offers strong attacks from both ends of the spectrum.
-Very good physical bulk - can switch into Dragon Dance Gyarados and Dragonite who have taken Stealth Rock Damage, take the hit, and OHKO both most of the time with Stone Edge or Ice Beam, respectively.
-Catches many opponents off guard, expecting a Curse or Support set; completely avoids being taunt bait.
-Excellent offensive coverage with EdgeQuake, Ice, and potentially Water.
Additional Comments:
-Expert Belt can be used to bolster its awesome type coverage, but you lose vital recovery.
-44/128 physical defense allows it to take boosted STAB from Gyarados and Dragonite (though Gyarados' Waterfall will leave you at a minimum of 15%)
Teammates and Counters:
-Swampert absolutely hates Toxic Spikes or Toxic. Tentacruel can be used to absorb Toxic Spikes and clear Stealth Rock and Spikes from the field, and leave Toxic Spikes of his own.
-As mentioned before, Stealth Rock is absolutely essential to getting specific kills on Dragonite and Gyarados, and only aid Swampert's attacks on different opponents.
-By virtue of being so slow, this set is not meant to sweep by any means. It helps punch holes in your opponents for other members of your team to pick off.
-Rotom-w can block Rapid Spin and put a hold on Heatran, who mostly pack Hidden Power Grass which demolishes Swampert.
-Traditional scouts like Choice Band Scizor help absorb a predicted Toxic from Blissey, and make a powerful exit with U-Turn.
-Toxic Spikes are literally thorns in Swampert's side, and Leftovers and lack of recovery don't compensate for this.
-Bulky grass types such as Shaymin and Celebi are a huge problem. You have no business trying to hit them with Ice Beam, but if you pack Avalanche and predict correctly, you can hit them on the switch