The Pokemon that evolve using a water stone:
Eevee
Starmie
Lombre
Poliwhirl, too...
For staryu to evolve you have to use a water stone
Lombre is one of the pokemon that do not evolve by level he evolves by using a water stone.
Seadra can be evolved into Kingdra by using a water stone
Lombre can evolve into Ludicolo with a Water Stone (Lombre can also be traded to evolve).
this also applyes for Pokemon sapphire and ruby and emerald he evolves at lv 14 into lombre and then use water stone so he evolves into ludicollo