Pokemon Diamond Cheat Codes

Hello all, I know there are probably tons of threads with questions that ask about codes for pokemon diamond, but I'm using an R4 and I was wondering what I could use to modify the pokemon I encounter. Thanks ahead of time.

umm use pokesav to get the pokemon you need O_ohttp://www.pokesav.org/main/

So does that mean that I would have to hack my save file... sorry I've never used Pokesav so I don't know what to do. And it'll work for R4?

^Yes and yes.