How this set isn't in the analysis is beyond me. We have a surprise special sweeper with Sludge Bomb and Shadow Ball but we don't have one like this? I threw this on a team with 3 Choice Scarfers in May, and found that its ability to weaken a large set of sweepers was INCREDIBLY handy. In fact, this was THE example of what people are referring to when they mention a "momentum shift." Sure, one on one it loses to most sweepers like SD Chomp and really offensive DD Gyara, but the bottom line is that it weakens both to the point that they no longer are relevant threats, and therefore allow you to maintain the pace of the battle.
http://www.smogon.com/dp/pokemon/weezing
[SET]
Name: Elemental Weezing
Move 1: Thunderbolt
Move 2: Flamethrower / Fire Blast
Move 3: Hidden Power Ice
Move 4: Explosion / Pain Split
Item: Leftovers
EVs: 252 HP / 176 Def / 80 SpA
Nature: Lax
[SET COMMENTS]
<p>This set's purpose is primarily to be an "all sweeper buffer," something that can save a very frail (yet fast) team from being swept by the standard offensive threats like DD Gyarados, DD Salamence or Swords Dance Garchomp. However, it isn't merely a centralized sponge; it can effectively counter physical fighters such as Lucario, Heracross and Gallade (assuming no Psycho Cut) and it actually beats most Gyarados one on one.</p>
<p>Thunderbolt hits Gyarados; HP Ice hits physical Salamence and Garchomp; Pain Split is for pseudo healing and Explosion is for dealing massive damage when at low health; Flamethrower hits Heracross, Lucario, Metagross, Skarmory, Forretress, Abomasnow, and Roserade for Super Effective damage, while Fire Blast can guarantee a OHKO on Abomasnow and a 2HKO on Roserade.</p>
<p>80 Special Attack EVs are given to 2HKO standard Skarmory with Flamethrower and 2HKO standard Yache Berry Garchomp on average, as Weezing will do 33.5% the first time and 67% the second time.</p>
<p>Pain Split versus Explosion is chosen simply according to stylistic preference. If scraping by and surviving as long as possible is the style of play, then by all means choose Pain Split. However, note that Explosion can help deal massive damage to late game stat boosters and allow a no risk switch in to the appropriate counter, since Explosion faints Weezing.</p>
http://www.smogon.com/dp/pokemon/weezing
[SET]
Name: Elemental Weezing
Move 1: Thunderbolt
Move 2: Flamethrower / Fire Blast
Move 3: Hidden Power Ice
Move 4: Explosion / Pain Split
Item: Leftovers
EVs: 252 HP / 176 Def / 80 SpA
Nature: Lax
[SET COMMENTS]
<p>This set's purpose is primarily to be an "all sweeper buffer," something that can save a very frail (yet fast) team from being swept by the standard offensive threats like DD Gyarados, DD Salamence or Swords Dance Garchomp. However, it isn't merely a centralized sponge; it can effectively counter physical fighters such as Lucario, Heracross and Gallade (assuming no Psycho Cut) and it actually beats most Gyarados one on one.</p>
<p>Thunderbolt hits Gyarados; HP Ice hits physical Salamence and Garchomp; Pain Split is for pseudo healing and Explosion is for dealing massive damage when at low health; Flamethrower hits Heracross, Lucario, Metagross, Skarmory, Forretress, Abomasnow, and Roserade for Super Effective damage, while Fire Blast can guarantee a OHKO on Abomasnow and a 2HKO on Roserade.</p>
<p>80 Special Attack EVs are given to 2HKO standard Skarmory with Flamethrower and 2HKO standard Yache Berry Garchomp on average, as Weezing will do 33.5% the first time and 67% the second time.</p>
<p>Pain Split versus Explosion is chosen simply according to stylistic preference. If scraping by and surviving as long as possible is the style of play, then by all means choose Pain Split. However, note that Explosion can help deal massive damage to late game stat boosters and allow a no risk switch in to the appropriate counter, since Explosion faints Weezing.</p>