Nintendoji (任天童子) is a great game and an impressive feat by Nintendo for the DSiWare platform. Unfortunately, it’s incredibly inaccessible.
You can find my item guide on google sheets, as well as a stream of me using it to play Nintendoji.
Check out the full nJoy walkthrough for more guidance.
Here’s the official Nintendoji manual.
DeepL can often be used for more accurate machine translations than Google Translate. Though it’s far from perfect.