well the most rarest pokemon i would say is unixe azelf and mespirt they suck i know but there the rarest in the game and dialga and girantina are rare to but not as rare as mespirt, azelf and unixe.
If its Dialga, use the master ball. for Azelf, Mesprit and Uxie, use Ultra/Timer balls.
For a normal Pokemon you should probaly use an ultra ball or great ball
you can use a cheat code
You can find the bestest,rarest, Pokemon is to go to www.marriland.com/pokemon
you can't catch it because you already beaten the legendary
you can catch a lot of unknown Pokemon A-Z
you cant catch it in gold if its a boy you can catch it in blue if its a girl you can catch it in purple
You can't catch dusknoir to get one trade dusclops.
The rarest Pokemon is Dialga
kyorge
regigigas
yes, you can catch Pokemon in Pokemon diamond
You cannot catch Celebi in Pokemon Diamond.
arceus, or slowpoke, who is quite rare.
The starter Pokemon or spritomb
Arceus Shaymin
neither of them is better, they are both the same, but in diamond, you catch dialga, and in pearl, you catch palkia, and you can catch different Pokemon in each game for example: you can catch this Pokemon in diamond, but not pearl but: you can catch this different Pokemon in pearl, but not diamond
You can catch makuhita in the fighting area in Pokemon diamond
You can find the bestest,rarest, Pokemon is to go to www.marriland.com/pokemon
How do you get a cherrim in Pokemon diamond.