This achievement will be your very first to pop!
As soon as the game loads up you will watch a short cut scene with Commissioner Gordon, he will then move onto the prison area where he’s asking for help with a specific hidden inmate.
You will be give the custom 1 option as seen below:
You then will be asked to select your characters custom body parts just keep accepting with
, and then give them a name.
Game clip below to show to confirm:
Sorry, this Game Clip has been removed
Then yes that magic pop achievement unlocked!