You take Piplup as a starter, and level it up. Other than that, if you're not using cheats codes, that's it.
unless you cheat you have to evolve piplup which is a starter Pokemon
Prinplup
You have to choose Piplup as starter pokemon, that you receive from Prof. Rowan, then at level 16 it will evolve into Prinplup.
by the Pokemon mansion in a double battle outside of it
With a Budew.
level 32
If you chose Chimchar as your starter, your rival will eventually get a Prinplup. Also, at the Pokémon mansion, one trainer will have a Prinplup.
you must start with a piplup and lvl it up until it evolves into prinplup and then into empoolion
U can't catch prinplup u only can evolve it from piplup and to get piplup is to cheat or at the start of the game u choose piplup as the starter hope this helped :)
You have to trade it over from a 4th gen game (Diamond/Pearl/Platinum) or from a friend. You can't get a Prinplup otherwise.
http://www.serebii.net/platinum/nationaldex.shtml Go there, and scroll down. There is a list of Pokemon for the pokedex, and their locations to see / catch them.
Prinplup evolves into Empoleon at level 36.