Let's see, as of western releases of One Piece games:
One Piece Grand Battle (PS1) was released in Europe.
One Piece Round the Land (PS2) was released in Europe.
One Piece Grand Battle RUSH (PS2/GC) was released in America/Europe with the 4kids treatment as "One Piece Grand Battle".
One Piece (GBA) was only released in America.
One Piece Grand Adventure (PS2) was only released in America/Europe.
One Piece Pirates' Carnival (PS2/GC) was released in America/Europe with the 4kids treatment.
One Piece Unlimited Adventure (Wii) was released in America.
One Piece Unlimited Cruise 1 & 2 (Wii) were released in Europe.
One Piece Gigant Battle (NDS) was released in Europe.
One Piece Pirate Warriors (PS3) was released in America/Europe (America only got digital distribution).
One Piece Unlimited Cruise SP 1 & 2 (3DS) were released in Europe.
One Piece Pirate Warriors 2 (PS3) was released in America/Europe (America only got digital distribution).
One Piece Romance Dawn (3DS) was released in Europe and will be out in America next month.
And I think that's it, every european release is in english except for Round the Land which I can't confirm since I only know the version which is German/Italian/Spanish.
If it's just "Grand Battle" games you're interested in, the first one on the PS1 and Gigant Battle (which is based on the PS1 Grand Battle games) are the ones that got released in english but not in America.