Getting Mudkip in Pokémon Diamond (DS): Impossible — Choose Piplup Instead

Mudkip is unobtainable in Pokémon Diamond. It's a Hoenn starter (Ruby/Sapphire/Emerald). Diamond's water starter is Piplup.

How to Get Piplup

1. Choose Piplup as your starter at game start.
2. Trade with a friend who chose Piplup.

Inter-generational trading requires Pokémon Bank/Home (for compatible games) or legacy Wi-Fi (discontinued). Normal gameplay only yields Sinnoh-region Pokémon.