Here’s a deck that I think will fare quite well when the HGSS set comes out. Omar has run a similar “Lady Gaga” Deck, but I can’t condone such behavior (because of the name). Let’s just focus on the Dialga Garchomp Deck for now. We will start with the following deck that Omar has built and tested, which he posted about before.
Pokemon: 19
3 Luxray GL
1 Luxray GL Lv. X
2 Garchomp C
1 Garchomp C Lv. X
2 Bronzong G
1 Dialga G
1 Dialga G Lv. X
2 Uxie
1 Uxie Lv. X
1 Toxicroak G (Promo)
1 Lucario G
1 Crobat G
1 Unown G
1 Azelf
Trainers/Supporters: 29
4 Cyrus’s Conspiracy
4 Roseanne’s Research
4 Energy Gain
4 Poke Turn
4 Power Spray
3 SP Radar
2 Night Maintenance
1 Aaron’s Collection
1 Bebe’s Search
1 Luxury Ball
1 Expert Belt
Energy: 13
4 Call Energy
4 Electric
2 Psychic
2 Warp Energy
1 Metal
The thing is that this is a fairly known deck by now. There isn’t a whole lot to say about it. Luxray can Bright Look up an opposing Pokemon and pretty much own it in one shot with either Trash Bolt or Flash Impact. Garchomp C Lv. X heals your SPs while adding an 80 damage Dragon Rush snipe attack. Dialga is a bit more situational and defensive shutting down trainers with its Deafen attack while also shutting down Poke-Bodies with its own Time Crystal Poke-Body. This all adds up to another potent SP deck. Have you noticed a theme yet? Take Luxray GL Lv. X. Mix it with some other SP Pokemon. Win.
If you want to keep winning, though, you’ll have to adapt for the changing environment. Heart Gold / Soul Silver is coming out, and it’s bringing some new cards into the format. How can we build a winning HGSS Dialga Garchomp Deck? Well, the easy answer is to take out 4 cards, add in 4 Double-Colorless Energy (or DCE), and then just roll. Are there any other new cards that we ought to consider? Is the metagame going to change enough to warrant a shift in this deck?
Many people believe that the more Dialga-heavy (and I think therefore more controlling) version will be a better choice come DCE time. Dialga and Garchomp both get a nice boost from the Double-Colorless Energy. Dialga G’s Second Strike and the Lv. X’s Remove Lost both have a double colorless component. Remove Lost can even remove your opponent’s DCE. Garchomp C only requires colorless energy, so DCE gives him quite a nice boost. Even Luxray GL’s Bite and Trash Bolt attacks have a double colorless requirement. In most of these cases, the DCE doesn’t really combo with Energy Gain, so it works as more of a replacement for EGain. Garchomp C (and Lv. X), however, can now do an attack that would seem to cost 3 energy by dropping EGain and DCE, so Dragon Rush can do 80 to a benched Pokemon in one quick move. It doesn’t even have to discard 2 energy cards to do it (if you only have a single attached).
Let’s discuss it a bit and see if we can come up with a nice new Dialga Garchomp Decklist for HGSS. Here’s the workshopped version.
Pokemon: 20
2 Garchomp C
2 Garchomp C Lv. X
1 Bronzong G
3 Dialga G
1 Dialga G Lv. X
2 Uxie
1 Uxie Lv. X
1 Toxicroak G (Promo)
1 Lucario G
1 Crobat G
1 Skuntank G
1 Unown G
1 Azelf
Trainers/Supporters: 27
4 Cyrus’s Conspiracy
4 Roseanne’s Research
4 Energy Gain
4 Poke Turn
4 Power Spray
3 SP Radar
1 Night Maintenance
1 Aaron’s Collection
1 Bebe’s Search
1 Luxury Ball
Stadiums: 2
2 Snowpoint Temple
Energy: 11
2 DCE
1 Psychic
3 Metal
3 Special Metal
1 Warp Energy
Ed 
Omar 