TheZZAZZGlitch | Pokemon Emerald: Arbitrary code execution - warping to the Hall of Fame @TheZZAZZGlitch | Uploaded July 2014 | Updated October 2024, 4 days ago.
Finally. This method is TAS-only though.

Code: pastebin.com/raw.php?i=Rn6tANQV
More information: youtube.com/watch?v=m9pvNYdhldo

Replace the asterisks in 17th and 18th nickname with the savefile's valid checksum of section 1 (to predict it before saving, luck manipulation and savestates are needed).

To calculate the right checksum to use in the code:
1. Make sure your save meets the requirements listed in the previous video (check if GBA address $E118FF4 has the value of $06)
2. Read the little-endian halfword at address $E003004. This is the map number.
3. Read the little-endian halfword at address $E003FF7. This is the previous checksum.
4. Subtract map number from 0x0B10 (taking negative values into account), and add the result to the previous checksum. This is your new checksum.