Instructions
Capture the wild Pokemon you encounter. You will also earn new Pokemon from gym battles, other trainers and various story events.
Complete the Sinnoh Pokedex. This list is comprised of 210 Pokemon, all of which are found somewhere in "Pokemon Platinum." You must complete the Sinnoh Pokedex to unlock the National Pokedex, which contains all 493 Pokemon in existence at the time "Pokemon Platinum" was published.
Explore areas of the game at different times of day. Some Pokemon can only be captured at night, while others may only show up during daylight hours.
Trade Pokemon with a friend to add new entries to your Pokedex. You can also make Pokemon hold special objects during trades, which will in turn force them to evolve into rare forms.