Yes you can. Turtwig is a starter pokemon, just like Pokemon Diamond or Pearl.
You can not get a Turtwig egg in Pokemon Platinum. But if you breed a Turtwig with a Ditto, then it is possible.
Breeding Turtwig with another compatible Pokemon.
You get Turtwig as a starter from Pokemon Diamond, Pearl, and Platinum.
starter Pokemon
You can't find Turtwig in the wild. You have to choose it from the starters Pokemon.
You choose it as your 1st partner Pokemon.If you didn't choose Turtwig then you will have to tradewith overs that have Pokemon pearl, diamond or platinum.
Turtwig, Chimchar, and Piplup.
Chimchar, piplup, and turtwig.
at the begining of the game the profeser will give you three Pokemon and you have to pick one and those three Pokemon are turtwig chimchar and piplup and if you want turtwig pick turtwig.
Turtwig is a starter pokemon in Diamond/Pearl/Platinum, Torterra is one of the evolved forms of Turtwig.
210 from Turtwig to Giratina
turtwig,chimchar,and piplup