Yes, use pal park and have the Pokemon you want to transfer in the PC.
Go to the computer then to Bebe's PC and then Move Pokémon and then pick a Pokemon and click on release.
You can get Pokemon diamond for PC from www.roms.zophar.net/Nintendo-ds/all
if you mean can you get Pokemon from pearl and diamond and trade them to ruby so you can get diamond and pearl Pokemon on ruby. then no you can not. but you can migrate ruby Pokemon. you put the Pokemon in ruby that you want to put on diamond or pearl in the PC. save it turn off. then go to diamond and migrate them. must be in ds at the same time. pal park.
To release a Pokemon in Pokemon Diamond version you must deposit it in your PC and then click on it with your white arrow. Options should appear in a list, select "release" and then it will say: "Are you sure you want to release this Pokemon?" select "yes" and then...Bye Bye Pokemon!
Ash has 6 Pokemon in Diamond version
you would have to set loose some Pokemon in order to make room for other Pokemon.
I dont have pokemon diamond
no way
u can't get a lvX Pokemon in diamond version
you need to have the sapphire version in the gameboy slot and the diamond version in the other slot
If you have the Pokemon Diamond Version booklet go to the content page and look up how to migrate .