I've been playing around with the scripts a bit. I borrowed a few from the Pokémon starter kit (the resolution modifying script and the ones it needs to work), and so have managed to change the resolution.
After messing around with the battle system, I think that 320x240 is a bit too small. I think we could use 480x320, which has half the screen area of default RMXP, but four times that of a GBA screen. A lot of the Digimon sprites don't even fit on the DS screen, so having a larger screen size might be useful.
However, this means I'll probably have to recode the systems completely, which will take some time. Also, it might be a good idea to use 32x32 tiles, like RMXP does by default. Yes, this means a lot of tile work, but we could probably find some nice tiles and only need to make our own for Digital World oddities.
I'm probably going to start the battle system from scratch anyway, since the default one is not that good at handling animations.