Question

In Pokemon xy can the name rater change your Pokemons Nickname Back to it's default name?

Answer 1

Yes, they can (although you'll have to enter it manually as there is no button you can press to do it instantly).

Of course, if the Pokemon you are trying to change's original trainer was not you, you won't be able to change that Pokemon's nickname, even if you are just changing it back to default,

Comments

Actually if you click on the Pokemon Sprite (top left) while nicknaming it, it changes the nickname to its original name. Learned this by experience.

Answer 2

Yes, just go to him, type in the original name like you do if you want to normally change it, and poof, you have it's original.