Well, the starter pokemons are strong and special in there own way , you just need to take care of them and train them, so i what i'm saying is their all strong.
the strongest Pokemon is arceuse
I think arceus is the the strongest Pokemon in diamond and pearl. Also no moves are supereffective on Spiritomb and arceus
Torterra and Golem are a few good choices
There is are no certain Pokemon needed to defeat the elite four. Just use your strongest Pokemon.
In a Pokemon battle, you should start with the weak Pokemon to weaken the foe for the your toughest.
the strongest Pokemon is arceuse
Some of the strongest Pokemon trianers in Pokemon diamond & paerl
Diamond is not a Pokemon but i think Arceus is one of the strongest Pokemon ever.
arceus
By leveling up your Pokemon from eggs.
shier piller
ARcues
I think arceus is the the strongest Pokemon in diamond and pearl. Also no moves are supereffective on Spiritomb and arceus
the strongest Pokemon are Salmence lv100 and Slakazem lv99 i should know because i have beat the Pokemon league 4 times only with these 2 Pokemon.
In Pokemon Diamond i say Torrterra is the strongest grass and ground Pokemon because i have a level 100 one and it's great.
Piplup: it is easiest to start off with since it evolves slowly so you can train it. Turtwig: it is in the middle Chimchar: it is hardest but it is the strongest (and also my favorite ^.^)
when you battle Pokemon champion Cynthia in Pokemon pearl,platinum,and diamond her strongest Pokemon is garchomp