...Not exactly what I was searching for, honestly.
I've opened my HeartGold ROM with Spiky's DS Map Editor (SDSME), and there's almost a thousand different scripts - I'm trying to find the script(s)/function(s) that handles "call a Gym Leader on specific day and time period to arrange a rematch" (in order to remove the day/time requirements), the beginning of the game (to figure out how the game chooses Ethan or Lyra for PC), and Fighting Dojo (to prevent Gym Leaders from leaving once battled).
I'd like to locate them via text references (i.e. "which script/function uses Text 219?"), but annoyingly enough multiple scripts use "Message 0x2" and "Message 0x3" instead of pointing to specific Text numbers, making that approach all but impossible. I don't know how else to narrow the three things I want down.