OriginalHamster had this cheat uploaded in this thread, second post, and
nixzero did the same with a bunch of codes with different control schemes:
https://gbatemp.net/threads/need-he...untry-returns-classic-controller-code.359292/
I have a PAL version of the game, and the codes are different for each region, so I can't try them myself. I hope they work well!