your rival (if u started with chimchar)
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.
by the Pokemon mansion in a double battle outside of it
A trainer on Route 212 near Mr. Backlot's Mansion will fight with a Prinplup when you battle them.
On the west side of route 212, in front of Mr Backlots mansion there is a couple who own one! :D
there is a trainer on route 212. It is the 2nd trainer heading south from hearthome after you get into where it gets darker/raining
Level 36
It evolves at level 16,To Prinplup (Evolve Prinplup to Empoleon at 36) :)
you have to have a ditto and prinplup or empoleon
Prinplup
a few do, but if you choose infernape as your first pokemon, your rival (wally) will have piplup, that will evolve into prinplup, hope that answers your question
level 32
Nowhere You Have 2 Evolve Piplup