There are many Water Type Pokemon in Pokemon Platinum, however, there is only one strongest one. That Pokemon is Palkia. Palkia is one of the Main Storyline Legendaries in Pokemon Pearl, it is a Water/Dragon Type. If you are looking for the strongest Non-Legendary, your best bet is Gyarados. Any exceptions?
Gyarados is a Water and Flying type Pokemon.
Ligtning type moves, and grass type moves are super effective against water.
Grass type Pokemon of course!!!!!!!
If you were talking about brain speed and you were a Pokemon it would be you. Deal with it.
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
Feraligatr is a Water type pokemon.
Buizel is a Water type pokemon.
Phione is a Water type pokemon.
Totodile is a Water type pokemon.
Tympole is a Water type pokemon.
Wartortle is a Water type pokemon.