There is no real way to get groudon, but you can just migrate it, or have a friend trade it to you.
groudon is in pal park in the mountain area
the only way to get groudon is to either import it from Pokemon sapphire/ ruby/ or emerald, OR, trade it from pearl/diamond/or platinum.
Piplup is obtained as a starter in Diamond and Pearl or through trades.
trade it from soulsilver
In Diamond & Pearl? Impossible without migrating, trading, or Action Replaying.
Groudon does not appear naturally within the game. Transfer it from Diamond pearl platinum soulsilver or heartgold.
Sorry, but Entei can not be obtained in Pokemon Diamond and Pearl itself, you must transfer it from old GBA games and use the Pal park in DP to catch him.
Put Honey on a tree
You have to migrate from Sapphire or Emrald.
you get groudon from a certain fossil
if you have action replay you will get to pick a pokemon so groudon is a hard pokemon you need the red orb for groudon on pokemon soul silver version or pokemon heart gold version but use action replay on pokemon pearl,diamond,platinum
Misdreavus cannot be obtained on Pokemon Diamond, so you must trade one from Pokemon Pearl.