You want the tanky one or offensive one?
For tanky water types:
Gastrodon - Only one weakness, with great HP and can also be quite offensive, and since your team has noivern and blaziken, i dont think grass would be a problem
Carracosta - Fossil revived in spinel town, Solid Rock can minimize SE damage, plus Rock typing is great offensively, with excellent defense, White Herb and Shell Smash combo ftw~
For offensive water types:
Empoleon -Piplup in 7th street event, great special attack and defense, and typing, but you've already got Klinklang, if you are not afraid of having repeated type, Empoleon can be great on your team
Azumarill - Huge Power can ditch out a great deal of damage, Mystery Egg content
Oh and also there is Ludicolo
Ludicolo - ability Rain Dish, and item leftovers/Big Root and Leech Seed(egg move, might have to breed) stall the heck out of opponent, with its somewhat decent HP and special defense~