Prinplup evolves into Empoleon at level 36.
You don't unless you evolve your piplup (level 16 i think). But, if you have a usb port and a usb wi-fi connection cord and do the set up, you can go to the gts and try to trade a Pokemon for a prinplup. Hope I helped!
it will evolve at level 21
It will evolve at level 48
Pachirisu does not evolve :(
Arbok does not evolve
level them up
At level 10.
level 44
level 26
level 26
Level 24
Level 48.