Sun Offense doesn't use stupid walls, let's PILE on the POWER.
Trait: Drought
EVs: 96 Hp/ 252 Atk / 160 Spd
Jolly Nature (+Spd, -SAtk)
Item: Life Orb
- Earthquake
- Stone Edge / Dragon Claw
- Fire Punch
- Thunder Wave / Swords Dance / Rock Polish
This variant of Groudon doesn't take any shit from Dialga. Most Dialga don't invest much speed at all, and hope to smash your standard 252/0 Groudon with Draco Meteor, or avoid the OHKO from an uninvested Earthquake. With 252 Atk EVs and Life Orb Earthquake will always OHKO 252/0 Dialga, and will always 2HKO 252/252 + Kyogre, meaning the Crogre will have a harder time and you won't be its bitch. the Speed EVs ensure that you outspeed 216 neutral natured Rayquaza, which is commonly seen on mix and mix DD (although the analysis says Hasty Rayquaza is the norm many people commonly opt for Mild to nab the OHKO on Groudon most of the time with Draco Meteor). The preference of Stone Edge or Dragon Claw is whether or not you want to hit Gira-O and do about 50% to Lugia, although Thunder Wave already cripples it. Both Dragon Claw and Stone Edge deal with Rayquaza regardless. In the last slot I normally use Stealth Rock, but since bojangles is a silly man with a silly vision I'd slash t-wave to be irritating for things like non-Crogre switch ins, Lugia, Palkia, Arceus. Rock Polish and Swords Dance deserve consideration for the multitude of switches that Groudon causes, but I'd probably stick with Thunder Wave.
There remains an obvious team mate in what every sun team needs: a Kyogre switch in. Now, there are 3 that one would consider from a non-hazard team - Palkia, Gastrodon, and Water-Arceus (don't use Grass Arceus on sun teams). Since Gastrodon is a complete deadweight against opposing sun I'd opt for either a Water-Arceus or a Palkia, and since we're taking the offensive approach we might as well use Palkia.
Trait: Pressure
EVs: 252 SAtk / 4 SpD / 252 Spd
Timid Nature (+Spd, -Atk)
Item: Lustrous Orb
- Fire Blast
- Thunder
- Surf
- Spacial Rend
no need for mix sets as when running a sun team a Palkia that can take advantage of both forms of weather is more flexible.
I'm going to suggest a no frills Ekiller Arceus as well, with Overheat to take advantage of the sun and Skarmory switch ins.
Trait: Multitype
EVs: 240 HP / 252 Atk / 16 Spe
Adamant Nature (+Atk, -SAtk)
Item: Silk Scarf
- Overheat / Shadow Claw
- ExtremeSpeed
- Swords Dance
- Earthquake
I think that the speed in the analysis in really superfluous, and even 132 speed is unecessary, positive natured + speed pokemon that aren't weak to ExtremeSpeed basically don't exist so 16 is all that you really need to outspeed neutral natured ones. The extra bulk afforded by this set lets you survive scarf Terrakions Close Combat most (i think, it might be all of) the time. Overheat in sun will maul Skarmory, even with a negative nature, but since we don't have Stealth Rock there's a higher chance of it having sturdy so we may opt in favour of just having the tried and true Shadow Claw. Or even Power Herb Shadow Force, which does mauls Giratina-A almost irreperably, and OHKO's Gira-O even with 252 Defense EVs.
The reason I chose Ekiller Arceus is that it's a very straight forward offensive force and does well in 'overwhelming' a lot of teams lacking a hard counter like Skarmory (which is set up bait for Reshiram) or Giratina-A.
Which brings me to
Trait: Bad Dreams
EVs: 252 SAtk / 4 SpD / 252 Spe
Timid Nature (+ Spe, -Atk)
Item: Leftovers / Life Orb
- Substitute
- Dark Void
- Focus Blast
- Dark Pulse
Something that completely messes up the physical walls like Lugia and Giratina-A that like to switch into Groudon and Ekiller, a simple sub lefties set will do wonders (opted over the NP sweeper set so it isn't simply picked off by a scarfer after sleeping something).