no
You can't unless you transfer it.
You do not catch deoxys in Pokemon ranger shadows of almia.
Arceas is first and i guess it is all the other legendary pokemons?
Ditto will hep you,just throw that game away and buy pokemon black.
darkrai arceas (with plate)
this site dosent know arceas is in soulsilver
trade pokemon
in my view i would have to say arceas (with plate) and dark rai
Arceas is thebeginningperson in Pokemon
the best way to get arceas in Pokemon diamond might be hard for you but i bet you'll think it was worth it! i have all the Pokemon on earth and arceas might have been the second hardest to get you have to get 3 dialga's and 3palkia's then put all of them in your party then they'll morph together then somehow they turn into one arceas!! i was as surprised you are!!! it may sound impossible but i speak the truth!!!!You can also you action replay which is a lot easier FROM FPM
You can't
Arceas
Yes, you can.
no
no its not the best deoxys is then dialgla then piklia
Palkia, Deoxys, Rotom, Arceas(sorry if i spelled it wrong), Uxie, Mesprit, Azelf, and Regagigas.