When you go to decorate and you drag certain items little oval things appear.
When you drag a Poke Puff there is a single oval in the middle which is the only place you seem to be able to place Poke Puffs.
The picture below shows the two ovals that appear when dragging a cushion.
What are these Ovals?
Best Answer
They are just predetermined positions for those items. Like if you are connected to the internet or your friends Pokemon visit your Pokemon Amie those circles are where their Pokemon sit. So these are the locations that the cushions should be.
The Poke Puff goes in the middle so all Pokemon can share. :)