If you start with piplup, empoleon. But if you start with a different Pokemon you can use Palkia. (legendary- hard to catch), Gyarados is easy to catch and good (you catch level 40-55 ones with a super rod.)
the best fire Pokemon in pearl version is chimchar ,monferno , and infernapeHeatron is also a good fire Pokemon
VICTORY ROAD IS BEST
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?
With Water-type or Flying-type
you use a water stone
blastoise is the best
the best Pokemon you can catch in Pokemon pearl is heatran
i think that the best Pokemon you can ever have in Pokemon pearl is Empoleon or Palkia not rare^ rare^
a super rod is the best rod in Pokemon pearl/dimond/platnim
You can get a Seel in Pokemon Pearl by finding it in the water on route 226.
it depends who your facing.
Pokemon pearl
The best water Pokemon would be empolean and tentacruel. But tentacruel isn't very good until it's in late thirties (level).
Giratina
palkia!
Water and grass
You cant