Well to add monsters to a scene you need to put them in there
For example if you want to import monster B from scene xyz in to scene abc you could tag it on the end of the enemies (monsters A)that are already in scene abc, but that would require abit of hard work (and maybe knowing where the Battle AI is would help). In addition you would have to hack the battle formations to add monster B alongside monsters A. I don't think battle formations has been hacked yet and AI is not quite there yet, so this venture would be very hard.
To add status effects I think you can search for that in the forums (Someone posted some values etc - L.Spiro I think) and hack the existing attacks to add status effects.