What is Pokesav?
Pokesav is a Windows application that can edit ("hack") Pokémon Diamond, Pearl, and Platinum save files. Any aspect of the save files can be changed, including Pokémon (and their movesets) as well as items. Pokesav can also generate Action Replay DS codes to provide the same effects as editing the save file directly.
Pokesav was developed by a Japanese programmer named COM and originally translated into English by GSD. ProjectPokemon.org has maintained English translations of the latest versions.
Why is Pokesav useful?
Pokesav can save hours of tedious training. For example, instead of having to breed a Pokemon and train it all the way to level 100, with Pokesav you can instantly create a Pokemon of any species, level, or moveset. It is also possible to use Pokesav to edit other aspects of the game such as the items and mystery gifts.
What is the difference between the different versions of Pokesav?
Because each game has a unique save file structure, there are separate versions for Diamond and Pearl/Platinum/HeartGold and SoulSilver/Black and White.
What do I need to use Pokesav?
In order to use Pokesav, you must have either an Action Replay DS or access to your save file, as detailed in this guide.
Is this against the rules to use in competitive play (is it cheating)?
The rules vary from league to league, however it's impossible to be caught by creating only legit looking Pokemon: hacked Pokemon that can't be differentiated from authentic Pokemon. In most leagues, however, use of a save editor is considered cheating. If you are not careful, you could get disqualified from a competition.
Being careful means keeping within the acceptable boundaries of the game, and not creating teams that are too outlandish (all shiny, 31 IVs for everything, etc.). It also helps greatly (whenever possible) to create hatched Pokemon instead of wild Pokemon, and to make very few edits to legitimate Pokemon. To be safe, don't change the IVs, hidden values, nature, gender, shininess, class, or ability.
Project Pokemon does not endorse cheating unless all opponents are fully aware you are cheating.
Can I create any Pokemon I want? With any moveset, ability, etc.?
With Pokesav, you have full control over the Pokemon you create. Every imaginable aspect of the Pokemon can be fully edited. (With a few exceptions, like Pokemon type)
Can I edit the game's code with Pokesav (ROM hacking)?
No. Pokesav only edits the save files of the game, not the code itself. Editing core game elements such as base stats, sprites, maps, and sounds is not possible by just editing the save file.
Is Pokesav compatible with older generations (Pokemon Ruby and Sapphire, etc.)?
Currently, Pokesav is only compatible with 4th and 5th generation games:
You can edit a Pokemon's Pal Park data to make it look like it was transferred from an older game, but Pokesav cannot directly interact with Generation III games.
What region games are compatible?
All regions should be compatible. If you are editing a Japanese version game, make sure your computer has the correct language packs installed and that you have a version of Pokesav that is compatible with Japanese characters. There are problems with Korean characters with the Korean version of Diamond and Pearl.
Can Pokemon created with Pokesav be used online?
Yes. However, the GTS and Pokemon Battle Revolution have built-in hack detectors. All Pokemon with reasonably legal stats should be able to pass Nintendo's hack checks, however.