I went to a Tournament in Las Vegas, NV @ Hobbytown USA.  There were 15-20 
people there and it cost $4 to get in.  Blastoise was 1st, Poliwrath 2nd, and 
Nidoking 3rd.  It was a 6 round Tournament, but each round wasn't best of 
three like it normally is.
Here is my deck!!
3x Squirtle
2x Wartortle
1x Blastoise
4x Magikarp
3x Gyarados
4x Poliwag
3x Poliwhirl
2x Poliwrath
1x Chansey
21x Water Energy
3x Double Colorless
4x Pokemon Trader
2x Potion
And I can't remember the other trainers, because I changed it.

I won 1st place so I got the Blastoise.  Here is what makes my deck so good:

At the beggining I send out Poliwag or Squirtle.  They can do little damage 
and Squirtle can Paralyze but besides that not much good.  If they aren't 
about to kill them then I can use Pokemon Trader To get a Wartortle or 
Poliwhirl unless I have 1.  Then I buff up someone, maybe let them kill one 
of mine then go for the KILL!!