It depends on what Pokémon you're trying to evolve. See serebii.net for more information. or see http://bulbapedia.bulbagarden.net/wiki/Main_Page.
If the Pokemon has the ability to evolve then it will evolve with a stone, when friendship is high or when it reaches a certain level.
Shaymin does not evolve in Pokemon Diamond.
A Magikarp should evolve at about lvl 40 on Pokemon diamond
no luvdisc can't evolve in diamond
snesel can'NT evolve but can evolve in Pokemon diamond, pearl and platinum snesel can'NT evolve but can evolve in Pokemon diamond, pearl and platinum
Rephrase your question = What level does snorlax evolve on Pokemon diamond? =
Absol does not evolve! :(
Roserade does not evolve.
yes it can evolve
It doesn't evolve.
Donphan does not evolve.
No, NO LEGENDARIES EVOLVE.
yes it can evolve