I'm back! Good news and a status report. Because of the battle glitch, I decided to try testing the 2P project on a new clean rom. I used a city for this. Here's was I tested.
For some weird reason, whever you talk to people, instead of facing you, they face the other dirction
If there is a person set to move randomly, both screens show different movement, causing both screens to show different locations if one was to run into the event..
Warps won't work at all.
Signs won't work at all.
Events work normally, but any added events will be glitched and hard to controll.
Shops work perfectly, the money is taken from the shopper and not the other player, items are distributed to the shopper and not the other player, no problems whatsoever.
It's not possible to encounter wild Pokemon, the grass doesn't even have an animation.
I haven't been able to test other aspects yet. It's clear that you can't have two people in 1P mode. I can't come to a conclusion yet but from the looks of it, expanded 2P areas are possible with strict limitations.
That's it for the status report. What do you think?