This is my water deck. How can I improve this deck?

19 water energy
1 double colorless
4 squirtle
3 wartortle
2 dark blastoise
2 psyduck
1 golduck
2 magikarp
1 gyrados
2 meowth (1 rocket, 1 jungle)
1 persian
2 krabby
1 kingler
2 staryu
2 articuno (fossil and promo)
1 lapras
2 bill
2 pluspower
1 switch
2 energy removal
1 super energy removal
1 pokeball
1 breeder
1 pokemond trader
1 prof. oak
1 potion

- - - - - -

I'll be honest with you, this deck needs alot of work. You have way too many singles and way too many evolution lines. Start off my dropping the following for the Pokémon:

-2 Dark Blastoise
-2 Wartortle
-2 Psyduck
-1 Golduck
-2 Magikarp
-1 Gyrados
-2 Meowth
-1 Persian
-2 Krabby
-1 Kingler
-2 Staryu
-1 Starmie
-1 Lapras

Most of the cards in this pile are very weak (besides Gyrados, but it has its downfall of having to start with Magikarp). Here are the key Pokémon cards you want to add for your Raindance to function at a competetive level:

+3 Cleffa (NG)
+3 Blastoise
+2 Wooper (NG)
+1 Magby
+1 Articuno

Please see my latest fix if you want to see why I like Cleffa so much. I do understand if you don't have any Blastoise (they're kinda hard to get your hands on nowadays), but it is by far the most important card in this deck. Without Blastoise, the archetype Raindance would never exist. Wooper is obviously to help counter Lighting Pokémon like the popular Rocket's Zapdos and Electabuzz. Magby is of course for countering annoying powers (Mostly Slowking).

By the way, make sure all of the Squirtle's are Team Rocket.

We have 10 slots left. Most likely we'll use the space up for some of the key trainers you're in need for.

Drop 4 Water Energy and the Double Colorless Energy.

On top of the 15 extra slots, drop the following:

-2 Bill
-2 Energy Removal
-2 Pluspower
-1 Pokéball
-1 Pokémon Trader
-1 Potion
-1 Switch

Bill is near useless in the current enviroment, especially since Cleffa has been with us for about a year now. Pokéball and Potion are even worse. They are extremely weak Trainer cards, that aren't even worth ranting about.

Wow, that gives us 10 more slots. Going to 25 open slots. Perfect. =D

Go ahead and add in these key Trainer cards, I'll explain them all in a minute.

+4 Item Finder
+3 Computer Search
+3 Professor Oak
+3 Gold Berry
+3 Lass
+2 Pokémon Breeder
+2 Super Energy Removal
+2 Gust of Wind
+2 Nightly Garbage Run
+1 Sprout Tower

That fills up the 25 slots. =D

Item Finder a.k.a My Favorite Trainer Card =D
For discarding two cards from your hand, you can get one Trainer card from your discard pile and put it in your hand. This card is so versatile, it's not even funny. You can get any Trainer card from your discard pile! This means additional Oaks, Pluspowers, Gust of Winds, SER's, any Trainer card of your chosing that's in your discard pile for just the small downfall of discarding any two cards from your hand.

Computer Search
Next to Professor Oak and Item Finder, this is one of the most broken cards in the game. For discarding two cards from your hand, you search your deck for any card. ANY CARD!! Enough said.

Pokémon Breeder
Put a Stage 2 Evolution card from your hand on the matching Basic Pokémon. Which of course means a turn 2 fully powered Blastoise. =D!!

Gold Berry
Heals big hitters with 50 HP and over. Between turns you discard Gold Berry and remove 4 damage counters (there must be 4 or more damage counters on the Pokémon to use it). Besides the fact that it heals your big hitters by 40 HP, it's extremely versatile. You can basically burn through your deck and play the Gold Berries in the process (one Pokémon can't have more than one tool attached though).

This card pretty much got the time of day when Cleffa was released. The Eeeeeeeek and Lass is the most common combo used in the current enviroment. Setup an active Cleffa, play Lass (making your opponent shuffle back all of their Trainers into their deck) and Eeeeeeek (giving you a brand new hand while your opponent is trying to recover).

Super Energy Removal
You discard one energy card off one of your own Pokémon in order for you to chose any one of your opponents Pokémon and discard any 2 energy cards attached to that Pokémon. Super Energy Removal is most effective against Steelix and Sneasel (or something that usese Darkness/Metal Energy).

Gust of Wind
Choose any Pokémon on your opponents bench and switch it with their active Pokémon. Used to pick off potential threats and to take apart the weak ones for easy prizes.

Sprout Tower
Since Sprout Tower is a Stadium card, it stays in play throughout the whole game unless it is countered by another Stadium. All damage done by Colorless Pokemon's attacks is reduced by 30 (after applying Weakness and Resistance.) A very good card against Clefable, Chansey and Wigglytuff.

Nightly Garbage Run
Choose up to 3 Pokémon cards and or Basic Energy cards from your discard pile and shuffle them into your deck. Useful against getting back discarded Blastoise's or Cleffa's from Computer Search/Item Finder.

Sorry about the History Lesson everyone, I just wanted to stress to him how good the above Trainer cards really are. ;x

Here's the deck list...

<Deck Name Here>

- Pokémon: 17
4 Squirtle (TR)
3 Blastoise
3 Articuno (F)
3 Cleffa (NG)
2 Wooper (NG)
1 Magby
1 Wartortle

- Trainers: 28
4 Professor Oak
4 Item Finder
3 Computer Search
3 Super Energy Removal
3 Gold Berry
3 Pokémon Breeder
3 Lass
2 Gust of Wind
2 Nightly Garbage Run
1 Sprout Tower

- Energy: 15
15 Water Energy

I Hope the deck works out for you.