On the site where I got my ROM they also included a link to a patch in executable form that apparently makes the game work
(I haven't got far enough to need this).
I've included an attachment, see if it works.
And if you're using an emulator, get the NDS firmware and BIOS, activate them in the settings, and use the other attachment to encrypt your ROM before playing.
(I had done that and got past the Oak Intro.)