Originally posted by Misdreavus
All names or just nicknames? If it is all names, will it keep its name with Japanese text or will it change its name to the Japanese version in English text (ex: Rayquaza ~ Rekkuuza)?

Basically, if I don't nickname my Pokémon, will it be just exactly as if it came from an English game?
The pokemon will keep the name with Japanese text. You will see the japanese trainer name and the japanese name of the pokemon even if you did not give a nickname to the pokemon. All in japanese letters of course.
To avoid both you can give the trainer an english name when you start the game. And whenever you capture or get a pokemon give it an english nickname. Notice, however, that you can only enter five letters for a name.