Pokémon have also had additions to their moveset, including additions or alterations to their level up movesets as well as TM and HM compatibility.
A lot of Pokémon have been given their Dream World abilities as an option, where applicable and/or useful. This can be a number of things, including experience rate, typing, base stats and abilities.
A vast number of Pokémon have had certain statistics about them edited.
The level curve takes full advantage of the new experience system in Black and White. While not mind crushingly tough, they're sure to provide more of a challenge than the original games were able to.
Every single trainer in the game has had their Pokémon edited, fitting a new level curve and increasing the difficulty overall.
This is unaffected by the version chosen to play encounters are the same in both.
As aforementioned, the hack allows you to catch all 649 Pokémon in some way or another.
Blaze Black and Volt White encompass a variety of differences to the original games.