Yeah so, i've been using this alot lately and it rarely fails to sweep.
It really deserves it's own set, I can provide logs if it's necessary.
http://www.smogon.com/dp/pokemon/porygon2
[SET]
name: Agility
move 1: Tri-Attack
move 2: Thunderbolt
move 3: Ice Beam
move 4: Agility
item: Life Orb
ability: Download
nature: Modest
evs: 56 HP / 252 SpA / 196 Spe
Why this set deserves to be on-site:
- Amazing mid to late game Sweeper, able to grab a +1 SpA boost and +2 Spe if you use download correctly.
- Unresisted Coverage(Bar Magneton and Shedinja)
- Base 105 special attack is fairly good.
- Great stab move that reaches 120 base power along with great effects.
- Reaches 410 Speed(specific benchmarks in powerwithin's post)
additional comments:
- Dark Pulse/HP fighting can also be used over IB/TBolt but not nearly as good.
- Recover?
teammates and counters:
- Hitmonlee/Top can take care of registeel and chansey.
- Fire and ground types such as dugtrio/rhyperior and Arcanine are good teammates to get registeel out of the way.
- Preferably spikes support as they help P2's sweep immensely.
- Registeel can wall you without hp fighting, however even with hp fighting you have to roll max damage twice to beat it with SR.
- Technitop can stop your sweep and kill you with fake out + Mach punch.
- Chansey walls you.
It really deserves it's own set, I can provide logs if it's necessary.

http://www.smogon.com/dp/pokemon/porygon2
[SET]
name: Agility
move 1: Tri-Attack
move 2: Thunderbolt
move 3: Ice Beam
move 4: Agility
item: Life Orb
ability: Download
nature: Modest
evs: 56 HP / 252 SpA / 196 Spe
Why this set deserves to be on-site:
- Amazing mid to late game Sweeper, able to grab a +1 SpA boost and +2 Spe if you use download correctly.
- Unresisted Coverage(Bar Magneton and Shedinja)
- Base 105 special attack is fairly good.
- Great stab move that reaches 120 base power along with great effects.
- Reaches 410 Speed(specific benchmarks in powerwithin's post)
additional comments:
- Dark Pulse/HP fighting can also be used over IB/TBolt but not nearly as good.
- Recover?
teammates and counters:
- Hitmonlee/Top can take care of registeel and chansey.
- Fire and ground types such as dugtrio/rhyperior and Arcanine are good teammates to get registeel out of the way.
- Preferably spikes support as they help P2's sweep immensely.
- Registeel can wall you without hp fighting, however even with hp fighting you have to roll max damage twice to beat it with SR.
- Technitop can stop your sweep and kill you with fake out + Mach punch.
- Chansey walls you.