Mystery Gift

Mystery Gift is an option on the menu screen which gives you the chance to receive special gifts.

Most of these give you Shinies, but there are a few others.

How To Receive
To receive a mystery gift, you will need a certain code, this code can be given to you from Sam or Dan (the creators of PTD). In this case, the code will be one time use only.

You can also find a code by following Sam & Dan Games' blog. Sometimes they announce a competition or something on their blog, the prize is often a Mystery Gift code, and can often be used as many times as you like.

Usable
Shiny Rattata: 01543on4

Expired as of v2.5
Shiny Pidgey: 5234

Shiny Jigglypuff: 673034

One per profile
Shiny Geodude: 5231

(Only works after you beat the pewter gym challenge mode)