Serebii.net is usually a good place to start but for an actual walkthrough just Google Pokemon diamond and pearl walkthrough and you will get multiple results
Any Pokemon with the little gender doohicky.
this at Pokemon diamond and pearl and platinum only go to sandgem town and there is a big house get in there and there is a little girl talk to her she will give all the information you need
the Pokemon that dawns little sister tells you
Pokemon on Pokemon diamond are like any other Pokemon, little creatures that you capture, battle with and train. To find some you just got to go looking?
the little girl at valley windworks will eventually get you a drifloon lv.20
i think a dude gives to you when it is still a little egg.
Pastoria
to get darkia get action replay same for the god and the little grass pokemon to get palkia (pearl) or dialga (diamond) it will be at the end of mt.cornet
Speak to Dawn's/Lucas' little sister, she will tell you about 15 different rare pokemon.
Talk to the little brown-haired girl in the Eterna City Pokemon center.
go to route 224 . it is in the caves little pond.
You need to go to Dawn's house and her little sister will tell you.