I'm too lazy to count :P
There are 9 total. Azumarill,Blastoise,Empoleon,Kingdra,Milotic,Sharpedo,Slobro,Suicune, and Swampert.
9 Pokemon in UU which are water. I counted.
Source: Experience and I checked the same link as MF but he put it on first -_-
Look at this.