>>537547415
picrel has examples of how everything sets a flag upon viewing/completing in if... for the sfc.
for some flags the game checks constantly to see if they're set.
looking at:
>2# = game clear (copied from $701813 on new game)
i assume after certain flags are set the game always reads from a certain ram address when selecting new gave and that ram address triggers the "ng+" content.
but again, this is a guess. and if you're curious, i got the ram map from romhacking.net.