1. Go into solo arcade, select party mode, choose any characters
2. Change item rate or quick/hard drop settings and start the game
3. Quit to main menu, then go to adventure mode
4. Select a scene with party mode, and those settings should be the same.
So far those are the only two settings I've found that carry over into adventure mode, doesn't look like anything carries over in swap mode. Using the switch version.

Cool idea, but it is unviable, because it would take too long with little pay off. Most party mode scenes have low level AI (not including the extra episodes) and can already be beaten with a few back-to-backs or T-spins. Just meet the score requirement and stall tbh.

Maybe if there was a way to guarantee pentominos it might be possible to gimp any later level party mode stages, but most of the items barely effect AI to begin with.

Just an observation, please don’t take it personal

If you can manage beating up the CPU in all the other levels handily, you don't really need to fiddle with the settings at all, unless you can change the duration of the match. That's about all I have to say on the matter, but it does sound fascinating; I wonder if it's possible to have quick drop for Puyo Puyo in modes other than Party and Tiny? That would actually be nice to have during story mode.