http://www.smogon.com/dp/pokemon/dialga
I've been using this set on my most recent team, and it's awesome, and has won me quite a few matches. Also, Smogon has no Lead Dialga Analysis yet,(that I know of) so here goes.
QC Accepted: 0/3
Grammar: 0/2
[SET]
Name: Bulky Anti-Lead
Move 1: Draco Meteor
Move 2: Flamethrower / Thunder Wave
Move 3: Thunder
Move 4: Stealth Rock
Item: Lum Berry
Nature: Modest
EVs: 252 HP / 244 SpA / 12 Spe
Why this set deserves to be on-site:
- Great for countering Common leads, such as Deoxys-S, Shaymin-S, Kyogre, Groudon, Darkrai, Forretress, and Rayquaza.
- Bulky enough to live hits that would normally OHKO offensive Dialga sets, such as Support Groudon's Earthquake.
- Able to carry Stealth Rock, something other Anti-Leads can't brag about.
- Able to come back late-game and wreak havoc.
- Works in both Sunlight and Rain.
Additional Comments:
- Draco Meteor is a great STAB attack with great covereage in Ubers.
- Flamethrower is great for Groudon, Forretress, Shaymin-S, and Metagross switch-ins. It's power Under the Sunlight can be deadly too.
- Thunder Wave is a good attack if your not worried about Forretress, but Flamethrower is preferred.
- Thunder 2HKOs Kyogre Leads, and hits Ho-Oh, Lugia, and Manaphy for Super-Effective damage if you come back late game.
- Stealth Rock is a must, everything on your team will appreciate it.
- The EVs give maximum HP and Maximum Sp.Atk. 12 Speed EVs are to always outspeed 8 Speed Groudon.
- If you are worried Groudon may be carrying some extra speed EVs, you could go with 36 Speed EVs, as this will also outpace Non-Choice Ho-Oh, albeit you'll sacrifice HP or Sp.Atk.
Teammates and Counters:
- Deoxys-A can SuperPower for the 2HKO, so a Priority user would be beneficial.
- Blissey walls this set all day, so a Wobbufet/Physical Attacker is needed.
- Mewtwo or Deoxys-S can set up Light Screen on you, so a Wobbufet/Pursuit user/something with Brick Break all help this set.
-This Dialga can lure in and Destroy Groudon, so Pokemon who appreciate Groudon's disposal, such as Swords Dance Rayquaza, Swords Dance Lucario, and Calm Mind Manaphy, make good partners for this set.
-If you Dislike Deoxys-S from getting Stealth Rock and 1 layer of Spikes on you, Forretress could be a good partner.
I've been using this set on my most recent team, and it's awesome, and has won me quite a few matches. Also, Smogon has no Lead Dialga Analysis yet,(that I know of) so here goes.
QC Accepted: 0/3
Grammar: 0/2

[SET]
Name: Bulky Anti-Lead
Move 1: Draco Meteor
Move 2: Flamethrower / Thunder Wave
Move 3: Thunder
Move 4: Stealth Rock
Item: Lum Berry
Nature: Modest
EVs: 252 HP / 244 SpA / 12 Spe
Why this set deserves to be on-site:
- Great for countering Common leads, such as Deoxys-S, Shaymin-S, Kyogre, Groudon, Darkrai, Forretress, and Rayquaza.
- Bulky enough to live hits that would normally OHKO offensive Dialga sets, such as Support Groudon's Earthquake.
- Able to carry Stealth Rock, something other Anti-Leads can't brag about.
- Able to come back late-game and wreak havoc.
- Works in both Sunlight and Rain.
Additional Comments:
- Draco Meteor is a great STAB attack with great covereage in Ubers.
- Flamethrower is great for Groudon, Forretress, Shaymin-S, and Metagross switch-ins. It's power Under the Sunlight can be deadly too.
- Thunder Wave is a good attack if your not worried about Forretress, but Flamethrower is preferred.
- Thunder 2HKOs Kyogre Leads, and hits Ho-Oh, Lugia, and Manaphy for Super-Effective damage if you come back late game.
- Stealth Rock is a must, everything on your team will appreciate it.
- The EVs give maximum HP and Maximum Sp.Atk. 12 Speed EVs are to always outspeed 8 Speed Groudon.
- If you are worried Groudon may be carrying some extra speed EVs, you could go with 36 Speed EVs, as this will also outpace Non-Choice Ho-Oh, albeit you'll sacrifice HP or Sp.Atk.
Teammates and Counters:
- Deoxys-A can SuperPower for the 2HKO, so a Priority user would be beneficial.
- Blissey walls this set all day, so a Wobbufet/Physical Attacker is needed.
- Mewtwo or Deoxys-S can set up Light Screen on you, so a Wobbufet/Pursuit user/something with Brick Break all help this set.
-This Dialga can lure in and Destroy Groudon, so Pokemon who appreciate Groudon's disposal, such as Swords Dance Rayquaza, Swords Dance Lucario, and Calm Mind Manaphy, make good partners for this set.
-If you Dislike Deoxys-S from getting Stealth Rock and 1 layer of Spikes on you, Forretress could be a good partner.