If by "strongest" you ment strongest Pokemon that would probably be Palkia if you ask me.
well if you ask me i think it would be arceus which you can get in action replay.
there is no strongest Pokemon because every Pokemon has weakness arceus is the strongest Pokemon in Pokemon pearl but can still be beaten
blastoise is the best
arceus
Arcues Any of them it depends how you train them.
Draco meteor
for me ubroan
ı think its infernape in sinnoh pokedex. ı think its infernape in sinnoh pokedex.
Earthquake and hyper beam
my opinion is lugia.
train your pocket monster really good and think about it.
you use your strongest pokemon and lots of potions
I think arceus is the the strongest Pokemon in diamond and pearl. Also no moves are supereffective on Spiritomb and arceus