How do you get caterpie in Pokemon Platinum?

Answer 1

You can trade, use the action replay for Pokemon Platinum, or actually catch it without the action replay. If you have completed the Sinnoh Pokedex, go and see Professor Rowan, and he will give you the National Pokedex, then you catch all the Pokemon throughout the land of Sinnoh from all the other regions due to an "outbreak". But, where to catch caterpie specifically, you need to go to Eterna Forest, west of Eterna City.