Fortunately, I've been preparing to play through a Japanese version of Pokemon Diamond. The Turtwig, Starly, and Shinx that I transferred to my US version of Diamond for training retained only their Japanese name and their Japanese OT. Moves, Abilities, Natures, all of those were English.Say I have a Japanese and an Amercian version of D/P. If I traded a Pokemon with a TM attached from the Japanese version to the American version, will the TM and the Pokemon's info such as nature, ability, moves, etc. be english?
Entertainingly enough, when the pokemon evolved, their names transformed into English (probably because I went with the default name, heh.)
Now, I assume the TMs / items will revert to their English name upon transfer but I'll admit I haven't tried it, yet.