The Anniversary Cake Pokemon was awarded to those who have been registered on PokeHeroes for 1 year. It was available from 2014 to 2017.
You could claim either a Cheese Cake Slurpuff or a Strawberry Cake Slurpuff, respectively.
It is not obtainable anymore.
|EHP:||EXP to level 100:|
|Cheese cake||Strawberry cake|
Anniversary Cake does NOT evolve.