There are two versions included in the download - one is for Diamond and Pearl only, and the other for PtHGSS only.

I'm not really sure where this tool came from but I know I used it to modify some sprites in HG/SS. PokeDSPic is a tool that allows you to look at graphical assets such as Pokémon sprites and export and import PNGs to modify them. Ignoring those things it's really, really good and pretty much necessary for any Gen IV hack. It's unfortunately not really in development anymore, so those bugs will probably never be fixed, but you can skirt around them. Known bugs in PPRE include the aforementioned script issues, not maintaining the PokéBall seal or ability (HG/SS only) values, messing up learnsets when saving a Pokémon with a full 20 level up moves, and incorrectly saving some of the fishing spots in Platinum and HG/SS. In these cases you may be able to simply save the map again in an older version of PPRE to compile the script correctly. However there are some issues with script compilation, particularly with movement commands that cause freezing ingame in HGSS. PPRE is the quintessential hacking tool for Gen 4, allowing you to edit Pokémon, trainers, scripts, overworlds, wild Pokémon and more. There are general DS tools in bond's thread that may also be of use. : Some tools supplied by Hiro TDK have been added.

(Besides some additions to a text file, at least.) I'm also happy to add any suggestions to the list. I've tried to add the authors of the tools wherever possible but I don't know all of them. The titles of the tools/resources act as the download links. If a developer has his/her tool listed here and doesn't want it to be, let me know and I'll take it off. I thought I'd compile a list of some of the tools I've used in the past as well as a couple others that I thought might be useful. I've been digging through some of my old files and found a bunch of tools and resources I used on my hacks, some of which the links seem to have been lost since.

Pokemon gba hack tools