Pokemon Pearl cheats and cheat codes for Nintendo DS

How to get all the Pokemon:
Sorry, you cannot get all in Pokemon Diamond.
You have to trade Pokemons from your GBA Pokemon games. 

You can catch all of the 4th generation monsters, but just
about 50 original Hoenn, Kanto, Johto pokemon.

You can change the time in the game by simply doing the following. 
When you start the DS go into the options and click the clock option 
then click the button that looks like a clock (not the alarm clock, thats
 the alarm) and change the time to what you would like. This cheat
 makes it much easier to catch night and day pokemon without having 
to wait a set amount of time.