Well, I recently got that Neo 9-Card Promo set, and one card in particular just struck me as incredibly great:
Odairu.
 
You may be scoffing, saying "10 for [WWW]? That's no good at all", but I strongly beg to differ.
 
His power/attack combined with massive drawing = insane amounts of damage.
 
So, I decided to build a deck around him: Water Mambo.
 
The decklist follows:
 
::12 Pokemon::
 
4 Waninoko
3 Arigeitsu
3 Odairu
2 Articuno (for quicker, back-up attacking)
 
::16 Trainers::
 
3 Prof. Oak
4 Bill
3 Gambler
2 Item Finder
2 Discard Exchange (from the Gym Leaders 2 set)
2 Pokemon Center
 
::32 Energy::
 
32 Water Energy
 
This deck is all about one thing: Insane, insane overkill with brutal blows of Reverse Flow. ;p
 
Use Oak, Bill, or Gambler to grab all the cards you can, evolve Waninoko to Odairu, put all that water energy into your discard pile, do upwards of 300 damage, and totally restock your deck with Water Energy.
 
Also, there's Discard Exchange, which can really be one nasty card: Say you've just used a Reverse Flow and your discard is devoid of water energy, you have all your card-drawing trainers in your discard, and your deck has ONLY water energy in it; Use Discard Exchange. Get back every single trainer, put all the water energy in the discard (where you were going to send it anyway. ;p), and use another attack from Reverse Flow.

The Pokemon Centers are for clearing off damage in times of desperation; since Water Energy is near-infinite in this deck, you don't have to worry too much about the discarding.
 
And last but not least, Item Finder. Pay the discard cost with Water Energy, get back that Oak, and.. well.. I think you get it by now. ;p
 
So far, this deck has only been beaten once (but a speed Scyther deck).
Anyway, lemme know what you think. I love this deck personally, it's a blast to play.
 
Send questions/comments to: mrtate@planethalflife.com
 
Note: For those who don't have access to a translation of the card [Odairu], i've provided one here:
 
Odairu, 120 HP
Lvl: 69    Stage 2: Evolves from Arigeitsu
Weakness: [G], Retreat: [CCC]
 
Pokemon Power: Downpour: You can remove Water Energy cards from your hand and discard them. You can use this power as many times as you wish during your turn. You cannot use this power if this Pokemon is Asleep, Paralyzed, or Confused.
 
Damage 10+: [WWW] Reverse Flow: Attack does 10 damage for each Water Energy card in your discard pile. After the attack, remove all Water Energy cards from your discard pile, put them back into your deck, and shuffle the deck well.