Lets see... Turtwig is weak to Candice, Elite Four Aron, and Elite Four Flint.
It is tough to Roark,Crasher Wake, and Volkner.(Remember, Turtwig's final form, Torterra,is half a Ground type!) Chimchar is weak to Roark (If it has not evolved Remember, Monferno, it's evolution, is a Fighting type as well.) It is also weak to Crasher Wake and Fantina . (Monferno and Infernape are half Fighting types, and Fighting types don't effect Ghost types.)It is also weak to Elite Four Beretha, and Elite Four Lucian.
(Infernape is also a Fighting type, and Fighting types are weak to Psychic types!)
It is tough to Roark,(If it has evolved into Monferno now.)Gardenia,Byron,Candice, and Elite Four Aron. Piplup is weak to Gardenia,Maylene(If it's an Empoleon by now) and Volkner. It is tough to Roark,Candice (Remember Empoleon is Half Steel type, and they have the advantage over Ice Types. It is also tough to Elite Four Flint, and Elite Four Beretha. (It is also weak to Beretha, because Empoleon is a Steel Type.)
OK FOLKS, NOW ITS TIME FOR THE RESULTS...
TURTWIG
Strong against... 4 people Weak Against... 3 people
CHIMCHAR
Strong against... 5 people Weak Against... 4 people
PIPLUP
Strong against... 4 people Weak against... 4 people
Yup. Turtwig is the best starter. Too bad for me, I chose Chimchar and now it's a Monferno. You might think Chimchar is the best, but according to my results, it's the worst. Piplup is what my brother chose, and it's a good choice.
Turtwig 1st
Piplup 2nd
Chimchar 3rd
There's no best starter. Just judge it on it's looks,how you like it, and pick.Also they all have equal power.
Chimchar
the best Pokemon to pick at the start is PIPLUP or CHIMCHAR
piplup is the best starter pokermon piplup is the best starter pokermon --------------------------- I chosed Turtwig grass type
The starter pokemon for Diamond and Pearl are Turtwig, Piplup, and Chimchar.
in order from best starter to worse Piplup Turtwig Chimchar
you can get it as your starter Pokemon
piplup
Choose it as your Starter Pokemon.
You have to choose it as a starter
I'm pretty sure that the only way to get another starter Pokemon in Pokemon diamond is to go to the Global Trade Station (GTS) and trade with someone.
A level 60 or up starter Pokemon dialgua or palkia and any Pokemon over 60 just not graveler
Turtwig in Pokemon Pearl and Diamond.