As someone who got introduced to Digimon with World 3 (painful I know lol).
I would just scrap the whole thing and make it a Story game mechanic wise.
Its baffling that theres so few playable Digimon in 3...
And also, too much backtracking, remove that too.
The plot was fine, but it was overshadowed by the fact that interesting stuff happens after you have backtracked for like 4 hours between each cutscene.
If it had the pace of Cyber Sleuth and a bigger Digimon roster, then it would easily be a good game.