Pokémon Diamond and Pearl Versions/Features

The day-night system first appearing in Generation II returns, with the same three time periods, but better transitioning between them. A new multifunction device called the Pokétch, short for Pokémon Watch, is also introduced. The regional 's name is Professor Rowan, after a tree like the others, and he allows the player and his or her rival to keep the starter Pokémon they used against attacking wild Pokémon at the beginning of the game.

A new battle system is used for Pokémon Diamond and Pearl. In this new battle system, attacks are declared either physical or special by how the attack itself operates, i.e. whether the attack touches the enemy or not, instead of the attack type, as was previously the case. For example, is now physical and  is now special. This was initially highly controversial with fans of the series, as it was considered to "waste" some of the Pokémon that were more powerful in Generation III, like and, though it now allows for a more versatile set of moves to be viable for these Pokémon.

Though it was reported initially that the games would feature Dark/Psychic/Fighting starters, this is not the case. The games retain the starters in the type trio of previous generations, Grass/Fire/Water, this time being, , and , respectively.