after you get the nationalpokedex go to canalave city.Go to the house by the sailor.The boy should be sleep.talk to the lady.Go to the sailor.He will ask to go to fullmoon island.say yes. there will be cressila .
cresellia is only in platinum, diamond and pearl
no
Go look for Cresellia
There is no such app, there is only an app which can show you where roaming Pokemon, such as Mesprit and Cresellia are, called the Marking Map (which can be obtained from the president of the Poketch company after obtaining the Veilstone badge).
The only way you can see all the Pokemon on diamond is by going into the GTS and global trade different Pokemon.
you have to catch all of the pokemon in diamond or SEE all of the pokemon
A Pokemon
The Pokemon you see do not go in your pokedex.
=== === === ===
No, you cannot see every Pokémon in the National Dex in Pokémon Diamond however you can see every Pokémon in the regional Sinnoh Dex in Pokémon Diamond.
for diamond and pearl there are 150 Pokemon u need to see . in plat nium u neeed to see 210 Pokemon.
You cannot see it in the wild in Pokemon Diamond; you have to transfer it from FireRed/LeafGreen.