In the options menu, there is a special option that allows you to put in a password. These passwords will unlock special extra stages across the game. These stages are visible beforehand but are shown with a lock by them so you cannot access them without the password. These stages have special Pokémon within them that cannot be obtained elsewhere in the game.
There are only four stages obtained via password and once you have redeemed all four, then the password option shall disappear forever. There is also a special Medal for accessing passwords.
|Mew||Area 04 - Stage 7||Japan||Weekly Famitsu||December 24th 2015||72398476|
|North America||Official Site||January 5th 2016||75603372|
|Europe||Official Site||January 5th 2016||18587211|
|Ash-Greninja||Area 03 - Stage6||Japan||Gathering in the Pokémon House||December 20th 2015||80930344|
|North America||Nintendo America Twitter||January 13th 2016||34111425|
|Europe||Official Twitter||February 28th 2016||89907383|
|Zygarde 10% Forme||Area 05 - Stage 7||Japan||7/11 - Seven Spot||December 15th 2015||75946452|
|North America||To be revealed||??||72005601|
|Europe||Official Twitter||March 3rd 2016||74326715|
|Zygarde Complete Forme||Area 05 - Stage 8||Japan||CoroCoro February Issue||January 15th 2016||15768352|
|North America||To be revealed||??||96734255|
|Europe||Official Twitter||March 1st 2016||77742314|