Piplup, Staru and many others.
Mudkip is a Water type pokemon.
Gyarados is a water type. Water type Pokemon are weak when battling a grass type Pokemon.
Surskit is a water type and bug type pokemon.
your starter pokemon can be a water type and you can trade water type pokemon with your friends in pokemon ruby
Water type Pokemon are weak to electric type Pokemon.
Electric
Buizel is a Water type pokemon.
Phione is a Water type pokemon.
Milotic is a Water type Pokemon.
Totodile is a Water type pokemon.
Piplup is a Water type pokemon.
Wartortle is a Water type pokemon.