Pal Park from a third gen game.
you can't.
i will what are you willing to trade
you cant you have to migrate it and u have to have the national pokedex in Pokemon diamond
come on do you have a brain that's a starter from a different region.
i don't think you can catch him unless you got heatgold or soulsliver where you get 3rd gen pokemon later on in the game
treeko isn't in this game
you cannot get a treeko in platinum but you can get it if you migrate from leaf green.
You can't. But you can trade with someone who has a treeko!
You can't. Treeko is only availiable in Sapphire, Ruby, and Emerald.
You cannot catch Grovyle in Diamond but the only way you can is by having Ruby,Saphhire or Emerald and having Treeko then evole it to Grovyle and migrating it to Diamond if you have Pal Park (south east of Sandgem) but the only way to go to Pal Park is to have the National Dex.
There is no way to get treecko unless its from ME Mystry event but you be able to get if you get pokesav you download it pokesav.org with a manual on how to use it
to get it in hoen you have to just get it from prof.birch in platinum migrate it from sapphire,emerald,or ruby.in diamond and pearl do the same thing as platinum.in firered and leafgreen you have to trade it from sapphire ruby or emerald.