The top five water Pokemon.  Well, three of them dash straight to the top of my mind.

1)    Feraligatr.   I know there's going to be some groaning here, but the truth is that he's just much more playable in this environment.  Grass weakness,120 HP, and in the right deck, any attainable amount of damage on the third turn.  He doesn't need any help from other Pokemon.  Misty's Wrath w/ Item Finders gets the job done, and Trash Exchange puts your trash in the deck, not to mention some damage in the discard.

2)    Blastoise.  Okay, technically, Blastoise is the better Pokemon.  Rain Dance on any other type would be incredibly phenomenol... but not water.  Nope, in water it's just really good.  Yeah, Blastoise, you are better than Feraligatr, but you're still number 2.  It's not you, it's your friends.  50 HP is the most you can dish out from a basic...? puh-lease.  (Sorry Arty)

3)    Wooper.  No, he's not an archetype of any kind, but he's just so versatile.  50 HP, a decent colorless attack, lightning resistance, and Amnesia... Goodness!  Put him in a deck that's weak to fire, or any old water deck.

4)    Ahhhhh... who cares?  There's lots of good water Pokemon out there.  But as far as Archetypes and staples go, there's really just not that many.  Misty's Gyarados is good, but the hold goes on it, plus you have those stinking Magikarps... Nevermind him.  I'm going to go with the new Suicune (if you don't know which one, you really are stupid)  It's probably the best basic that water has to offer (as far as actually dishing out damage).

5)    Kingdra... is not that great.  Personally, I'm more afraid of those darn Misty's Poliwhirl, Seaking, and especially Golduck... using those Misty's, PlusPowers, and Item Finders... It's just not right.  *How can a Poliwag do 140 damage on the first turn?* :*(