Well I was told once before that this was merely an "other options" type set, but considering I have now see at least four different people use this set, I am going to have to present it once more.
Here's Dialga:
http://www.smogon.com/dp/pokemon/dialga
[SET]
name: Supporter
move 1: Thunder Wave / Toxic
move 2: Stealth Rock
move 3: Draco Meteor / Dragon Pulse
move 4: Flamethrower / Thunder / Roar
item: Leftovers / Lum Berry
nature: Modest
evs: 252 HP / 176 SpA / 80 SpD
[SET COMMENTS]
<p>This set's purpose is to take advantage of Dialga's auspicious defensive typing and useful support moves. Since Speed is stressed in the Uber metagame, and the only consistently seen Ground-type is Groudon, Thunder Wave will shut down the opponent's sweeper. However, Toxic can be used over Thunder Wave to help Dialga cripple the aforementioned Groudon or the "Great Wall" Lugia, both of which will often switch into Dialga.</p>
<p>Draco Meteor over Dragon Pulse depends simply on whether Dialga is needed to continually hit the opponent, or if dealing massive damage is preferred. Note that Dragon Pulse will 3HKO most Kyogre, while Draco Meteor 2HKOs very rarely. The last slot depends coverage preferences. Flamethrower allows Dialga to hit Metagross, Forretress and the occasional Ninjask. Thunder hits all the Steels for hard damage anyway (besides Dialga), but also hits Lugia, Manaphy and Kyogre for Super Effective damage. Finally, Roar is an option simply for scouting various threats, such as Lugia (which will switch in expecting to counter the Bulk Up set) or Rayquaza (which will take 25% damage from Stealth Rock and be less of a threat in the late game without its surprise).</p>
<p>The defensive EVs ensure Non-Specs Kyogre's Water Spout will not 2HKO Dialga. This then allows Dialga to Thunder Wave, Stealth Rock and switch to the appropriate counter. While this set is an effective starter, it is more useful as a switch-in against common threats, such as Palkia, Giratina or the various Steels that are prevalent in the Uber metagame. </p>
Here's Dialga:
http://www.smogon.com/dp/pokemon/dialga
[SET]
name: Supporter
move 1: Thunder Wave / Toxic
move 2: Stealth Rock
move 3: Draco Meteor / Dragon Pulse
move 4: Flamethrower / Thunder / Roar
item: Leftovers / Lum Berry
nature: Modest
evs: 252 HP / 176 SpA / 80 SpD
[SET COMMENTS]
<p>This set's purpose is to take advantage of Dialga's auspicious defensive typing and useful support moves. Since Speed is stressed in the Uber metagame, and the only consistently seen Ground-type is Groudon, Thunder Wave will shut down the opponent's sweeper. However, Toxic can be used over Thunder Wave to help Dialga cripple the aforementioned Groudon or the "Great Wall" Lugia, both of which will often switch into Dialga.</p>
<p>Draco Meteor over Dragon Pulse depends simply on whether Dialga is needed to continually hit the opponent, or if dealing massive damage is preferred. Note that Dragon Pulse will 3HKO most Kyogre, while Draco Meteor 2HKOs very rarely. The last slot depends coverage preferences. Flamethrower allows Dialga to hit Metagross, Forretress and the occasional Ninjask. Thunder hits all the Steels for hard damage anyway (besides Dialga), but also hits Lugia, Manaphy and Kyogre for Super Effective damage. Finally, Roar is an option simply for scouting various threats, such as Lugia (which will switch in expecting to counter the Bulk Up set) or Rayquaza (which will take 25% damage from Stealth Rock and be less of a threat in the late game without its surprise).</p>
<p>The defensive EVs ensure Non-Specs Kyogre's Water Spout will not 2HKO Dialga. This then allows Dialga to Thunder Wave, Stealth Rock and switch to the appropriate counter. While this set is an effective starter, it is more useful as a switch-in against common threats, such as Palkia, Giratina or the various Steels that are prevalent in the Uber metagame. </p>