There have been some programs that can do some things with gba saves but they aren't in the mainstream...
That will enable the national dex, and let your pokemon evolve.
On another note, I just installed Dialga into my hack, and to test him I made up a script where this guy would give him to me. Problem is, he gives me an Illumise instead of Dialga...
So, the details.
-I stuck Dialga into the slot right after celebii.
-The relevant section of script reads: givepokemon 0x187 0x5 0x0 0x0 0x0 0x0
-I have not yet messed with the icon or cry.
-I have already installed the front and back sprites for Dialga.
-I also cannot edit Dialga's pokedex entry in any way; I don't know why.
My team has a tool that should help you.
I posted the thread I'm just waiting for it to be approved.
Click on the last userbar in my sig.
Got to tools.