Best cards in order? Here:
1. Ceilio's Network
This card is GOD in this format. Every deck needs at LEAST 3, but should run 4, unless it runs a heavy line of Milotic d or Gardevoir SW. It searches your deck for ANY Pokemon card. Bebe's is the only alternative...
2. Claydol GE
This is probally the best Pokemon. It's Power is godly, Wager makes almost no difference now. It can KO Pachis or Absols, both popular Starters. It has a decent Basic. What could go wrong?
3. Rare Candy
This card is a staple in EVERY Stage 2 deck, no exceptions. It automaticly Evolves one of your Basics in play to the Stage 2 or Stage 1 version, if you have the Stage 2 in your hand. This can be pretty powerful, especially with Claydol.
4. Double Rainbow Energy/ Scramble Energy
These two cards are tied. I'll review Double Rainbow Energy first: Double Rainbow Energy (DRE) is an AMAZING card. It provides two Energy at a time, every type/colour, at the expense of only 10 less damage. Although, that 10 damage can be the difference between winning and losing, that nearly never happens, and the extra speed is great.
Now Scramble Energy: Scramble Energy is great too. If you're behind on Prize Cards, it provides 3 Energy of any colour, no drawback. It lets you make a HUGE comeback, especially in Magmortar. Very nice.
5. Team Galactic's Wager
Though this card's usefulness has been severly cut, it is still a very good card. Claydol lets you recover from a loss in the coin flip/dice roll/RPS game, and it gets better when your opponent has a godly hand and you have nothing. Also, if you've mulliganned a couple times, you can Wager your opponent's larger hand away. Pretty cool, huh?
6. Gardevoir SW
Finally, an attacker! Gardevoir speeds up one of the best decks in the format, G&G, greatly, and without it, G&G would never work. Gardevoir copies any Supporter from your opponent's discard pile with Telepass. Two Ceilio's a turn sets you up VERY well. But the fun dosen't stop there. Gardevoir has a useful attack called Psychic Lock. It does a moderate 60 damage, but it has a great effect - it stops your opponent from using Powers. That can bring their setup to a grinding halt. Of course, Gardevoir has only one disadvantage. It has a low HP of 110.
7. Gallade SW
Gallade and Gardevoir go hand in hand, and so they make up G&G. Gallade has two attacks. The first is called Sonic Blade. It puts the Defending Pokemon down to 50 HP, and switches it out. This is okay, as then the opponent gets to attack you. But it's second attack, Psychic Cut, does more. It is probally the best attack in the format right now. What it does is a whopping 60 damage... with an effect, of course. You flip over as many Prize Cards as you like. For each Prize Card flipped over, it deals 20 MORE damage. This means that Gallade maxes out at 180 damage. It takes out everything in the format, other then Wailord. This is why Gallade is #7.
8. Gardevoir Lv.X SW
If Gardevoir was good, imagine the Lv.X form of it! Well, here it is. Gardevoir Lv.X is a great addition to G&G. It has an attack called Bring Down, that automaticly KOs the Pokemon with the least amount of HP remaining. This can be EXTREMELY powerful, as obviously you're not going to do it with a 30 HP Gallade sitting on your Bench. You're going sacrifice the Gallades, so you can later sweep with Gardevoir Lv.X. It's Poke-Power, Teleportation, is also very useful. It lets Gardevoir Lv.X switch out, from the Bench or Active, with something on the Bench/Active. That pretty much means it has free Retreat, as well as everything else in G&G.
9. Magmortar SW
Without Magmortar, Fire TRUK (Magmortar/Typhlosion/Delcatty) would never happen. It is THE best spreader in the game. It has an attack, called Fire Blast, that does 20 damage times the number of Fire Energy attached to it. That is it's 'Big Damage' attack. It's other attack is called Fireball Bazouka. It does a low 40 damage for 3 Energy, but it has an effect, of course. It also does 20 damage to 2 Benched Pokemon. This is it's 'Spread Attack.' Magmorar also has a Poke-Body that heals it by 20 every time you attach an Energy to it. This, combined with Magmortar's 110 HP, makes Magmortar VERY good.
10. Magmortar Lv.X MT
Magmortar Lv.X is a must in any Magmortar deck. It not only adds HP, but it has a great attack and Poke-Power. It's attack does 100 damage to anything for 4 Energy, discard 2. This might not seem so great, but when you're getting back that Energy through Typhlosion, it's great. It's Poke-Power is also amazing. It automaticly Burns the opponent when Magmortar Lv.X hits the field... but your opponent takes 3 Damage Counters from Burmn instead of 2 every time they roll/flip tails. That's amazing.
So there you go. You can easily switch the Magmortars with the Gard/Lade. But because I have not tested with Magmortar, this is how it is for now.