Some more random stuff I could find.
All three scientists are in the power plant, the third one pops a blank dialogue box for a split sec. I think the Substitute
guy in Rugosa also shows an odd blank spacing the first time you talk to him.
Talking to the policeman again before battling Grimer will trigger some blue dialogue box meant to appear (or so I think) after clearing the way.
The Statues inside Rugosa's gym can't be interacted with.
The Starmie Doll you can buy in Rugosa's vendine machine is a Staryu Doll.
I think I'm done with the demo now, got all six medals and I'm not finding anything else. Don't give up Peridot Anon. The Doll wont move even if I come back during night time, right? Maybe it would be a fun touch if the thing jumped upon talking to the little girl, while she isn't looking at it, maybe replace the old doll with a new one upon trading or re-entering the room
. Just some ideas, none that needs priority