The Dragon Gym-1 Uber, 1 Filler
Heatran @ Shuca Berry
252 SpAtk, 252 Spe, 4 Spe
Modest Nature
-Stealth Rock
-Fire Blast
-Earth Power
-Explosion
Shuca Berry is extremely necessary for Earthquakes. The given EV Spreads let Heatran use Stealth Rock and then show up later in the game against Weavile, Mamoswine, and Abomasnow and Fire. Or, show up on a Garchomp, and BAM! Asplode, yaaaay! Earth Power is a STAB, and the only STAB that fills the last slot.
Rayquaza @ Life Orb
Jolly Nature
252 Atk, 252 Spe
-Swords Dance
-ExtremeSpeed
-Dragon Claw
-Earthquake
The Salamence of Ubers. With Life Orb (even with Jolly Nature) and Swords Dance, he reaches a monstrous ~1554 Atk, capable of OHKOing even 252 Def Groudon. The Jolly Nature is to boost the Spe, giving it a respectable 317 Spe, at least outpacing BandTar. Even if you're up against a faster Dragon, ExtremeSpeed should take care of it, remember the attack. Dragon Claw is STAB, and Outrage isnt used because the confusion only adds to Life Orb damage. Earthquake is necessary on all Atk Dragons, so its there. Also, it OHKOs the Steel types that are definitly coming at a Dragon Gym.
Salamence @ Life Orb
Jolly Nature
252 Atk, 252 Spe
-Dragon Dance
-Outrage
-Earthquake
-Roost
The Life Orb is obvious-I won't give up the Boost for a Yache Berry, and I need Dragon Dance so Choice Items are not an option (those 4 items are the only things that CAN work on Salamence). The Jolly Nature is for Zapdos, and Adamant Non-Scarf Garchomp. The moves are obvious, you need Outrage for Power, and Earthquake just because you need Earthquake (No, think about it, what Mence DOESNT have Earthquake?). Fire Blast is replaced with Roost since I have no SpAtk EVs and Roost is just like Recover on a Latias: annoying.
Kingdra @ Lum Berry
252 Atk, 252 Spe
Jolly Nature
-Dragon Dance
-Substitute
-Outrage
-Waterfall
The idea here is to come out on a Pokemon that will switch to a statusing Pokemon. As they switch, I use Dragon Dance. As they status, Lum activates and I use Dragon Dance. As they attack, I use Substitute and Outrage and Waterfall. The nature is Jolly so that is outpaces alot of Pokemon.
If the opposing Pokemon does NOT Status, then confusion from the first Outrage is gone, woohoo! Also, the two moves are STABs and get everyone Pokemon with at least neutral damage, with the exception of Empoleon and Shedinja.
Latias @ Light Clay
238 HP, 252 Spe, 24 SpA
Timid Nature
-Reflect
-Light Screen
-Recover
-Dragon Pulse
Since practically every other Pokemon is Atk, I'd rather go full on Atk instead of 5 Atk, 1 SpA. So, this dual screener makes sure fragile Pokemon like Flygon and Kingdra dont get hurt too much from Ice Beam and Outrage. Also, this makes sure Rayquaza doesnt get OHKOd by Garchomps Outrage. This Latias isn't staying for the party as that is a waste of moves, but if its totally stuck, Dragon Pulse is used. This is only in emergencies, like an Mamoswine who you know will Blizzard or Ice Shard your already weakened from Life Orb Mence or from weakened Life Orb Rayquaza.
Flygon @ Choice Scarf
252 Atk, 252 Spe, 4 HP
Jolly Nature
-Outrage
-Earthquake
-U-Turn
-Stone Edge
Choice Scarf is because this fragile 80/80/80 Cannon can't survive any boosting moves, so Scarf is the only boost it can get. The EVs are obvious, maxamizing out all he has. Going for Adamant and not for Jolly is a good idea because his Atk is BST 100, so he needs all the boosts he can get. Outrage is PWN, Earthquake is neccessary (Isn't Earthquake neccessary on all Atk Dragons?), U-Turn is when the first thing Flygon is up against is something that can be faster and/or something that can OHKO it. Stone Edge is to faceown opposing Ice Types, but the only thing is that maybe the opposing Ice-Type is faster than it *ahem* Weavile *ahem* and has Scarf. In this case, I switch out to Heatran while they Ice Punch/Shard and do .25 Power, lol, and while they run away from Fiaaah Blast I return to Flygon or something stronger.
(P.S.: Goddamit, while I was editing Kingdra, Latias was down there doing her .gif sprite animation, and it was so annoying. Same thing with Rayquaza. I was like OKAY I GET IT YOU CAN DANCE NOW STFU.)

Heatran @ Shuca Berry
252 SpAtk, 252 Spe, 4 Spe
Modest Nature
-Stealth Rock
-Fire Blast
-Earth Power
-Explosion
Shuca Berry is extremely necessary for Earthquakes. The given EV Spreads let Heatran use Stealth Rock and then show up later in the game against Weavile, Mamoswine, and Abomasnow and Fire. Or, show up on a Garchomp, and BAM! Asplode, yaaaay! Earth Power is a STAB, and the only STAB that fills the last slot.

Rayquaza @ Life Orb
Jolly Nature
252 Atk, 252 Spe
-Swords Dance
-ExtremeSpeed
-Dragon Claw
-Earthquake
The Salamence of Ubers. With Life Orb (even with Jolly Nature) and Swords Dance, he reaches a monstrous ~1554 Atk, capable of OHKOing even 252 Def Groudon. The Jolly Nature is to boost the Spe, giving it a respectable 317 Spe, at least outpacing BandTar. Even if you're up against a faster Dragon, ExtremeSpeed should take care of it, remember the attack. Dragon Claw is STAB, and Outrage isnt used because the confusion only adds to Life Orb damage. Earthquake is necessary on all Atk Dragons, so its there. Also, it OHKOs the Steel types that are definitly coming at a Dragon Gym.

Salamence @ Life Orb
Jolly Nature
252 Atk, 252 Spe
-Dragon Dance
-Outrage
-Earthquake
-Roost
The Life Orb is obvious-I won't give up the Boost for a Yache Berry, and I need Dragon Dance so Choice Items are not an option (those 4 items are the only things that CAN work on Salamence). The Jolly Nature is for Zapdos, and Adamant Non-Scarf Garchomp. The moves are obvious, you need Outrage for Power, and Earthquake just because you need Earthquake (No, think about it, what Mence DOESNT have Earthquake?). Fire Blast is replaced with Roost since I have no SpAtk EVs and Roost is just like Recover on a Latias: annoying.

Kingdra @ Lum Berry
252 Atk, 252 Spe
Jolly Nature
-Dragon Dance
-Substitute
-Outrage
-Waterfall
The idea here is to come out on a Pokemon that will switch to a statusing Pokemon. As they switch, I use Dragon Dance. As they status, Lum activates and I use Dragon Dance. As they attack, I use Substitute and Outrage and Waterfall. The nature is Jolly so that is outpaces alot of Pokemon.
If the opposing Pokemon does NOT Status, then confusion from the first Outrage is gone, woohoo! Also, the two moves are STABs and get everyone Pokemon with at least neutral damage, with the exception of Empoleon and Shedinja.

Latias @ Light Clay
238 HP, 252 Spe, 24 SpA
Timid Nature
-Reflect
-Light Screen
-Recover
-Dragon Pulse
Since practically every other Pokemon is Atk, I'd rather go full on Atk instead of 5 Atk, 1 SpA. So, this dual screener makes sure fragile Pokemon like Flygon and Kingdra dont get hurt too much from Ice Beam and Outrage. Also, this makes sure Rayquaza doesnt get OHKOd by Garchomps Outrage. This Latias isn't staying for the party as that is a waste of moves, but if its totally stuck, Dragon Pulse is used. This is only in emergencies, like an Mamoswine who you know will Blizzard or Ice Shard your already weakened from Life Orb Mence or from weakened Life Orb Rayquaza.

Flygon @ Choice Scarf
252 Atk, 252 Spe, 4 HP
Jolly Nature
-Outrage
-Earthquake
-U-Turn
-Stone Edge
Choice Scarf is because this fragile 80/80/80 Cannon can't survive any boosting moves, so Scarf is the only boost it can get. The EVs are obvious, maxamizing out all he has. Going for Adamant and not for Jolly is a good idea because his Atk is BST 100, so he needs all the boosts he can get. Outrage is PWN, Earthquake is neccessary (Isn't Earthquake neccessary on all Atk Dragons?), U-Turn is when the first thing Flygon is up against is something that can be faster and/or something that can OHKO it. Stone Edge is to faceown opposing Ice Types, but the only thing is that maybe the opposing Ice-Type is faster than it *ahem* Weavile *ahem* and has Scarf. In this case, I switch out to Heatran while they Ice Punch/Shard and do .25 Power, lol, and while they run away from Fiaaah Blast I return to Flygon or something stronger.
(P.S.: Goddamit, while I was editing Kingdra, Latias was down there doing her .gif sprite animation, and it was so annoying. Same thing with Rayquaza. I was like OKAY I GET IT YOU CAN DANCE NOW STFU.)