Raindrops keep falling on my head... oh, sorry, got into a song mood *^_^*

Let's see what you have currently:

Pokemon (10 Basic + 9 Evols = 19 Total):
4 Squirtle
2 Wartortle
4 Blastoise
4 Magikarp
3 Gyrados
2 Chansey

Energy (23 Total):
23 Water

Trainers (18 Total)
4 Pokemon Breeders
3 Professor Oak
3 Super Energy Removal
3 Bill
2 Gust of Wind
3 Computer Search

Rain Dance is one of those decks that defy the standard ways of constructing decks.  It frequently uses the Blastoise and Gyrados lines to stomp the opponent quickly.  However, lately I've been finding another interesting pokemon to add to the mix.  Lapras.  It is a high-HP basic and has the wonderful ability to do 10 damage and a chance to CONFUSE!  No more problems with Mr. Mime... even Aerodactyl can be Gusted forward and confused to alleviate the problems it brings to the deck.  So, let's add this wonderful pokemon to our deck!  We're also going to remove Wartortle.  Your goal with a fast Rain Dance deck is Blastoise or Gyrados.  The middle stage of Wartortle isn't of interest to us.  So we'll use those slots to take advantage of more trainers.

Pokemon (12 Basic + 7 Evols = 19 Total)
4 Squirtle
4 Blastoise
4 Lapras
4 Magikarp
3 Gyrados

Energy (23 Total):
23 Water

Rain Dance decks have to have a very high mix of drawing trainers.  Energy Removal isn't needed in a deck that should be doing 60 damage by turn 2 or 3.  So, we'll scrap those in favor of some other cards.

Trainers (18 Total):
4 Bill
3 Professor Oak
3 Computer Search
4 Pokemon Breeder
2 Gust of Wind
2 Pokemon Trader

Good luck with this deck!