Japanese cards are legal for use.
If the backs of your cards do not match, you must sleeve in solid backed sleeves
the Lucario and Regigigas sleeves will not be allowed for that, as they are translucent. Also the Arcanine sleeves that are from Ultra Pro, those are translucent also.
In order to use, you MUST have an outside reference of the card, either a copy of the card in english with the same art, or a copy of the page out of the Card-dex which is avaliable at http://www.go-pokemon.com Just go to your player resources to see the pdf's of the card-dex.
~Duke