saucercrab said:For general template stacking guidelines, go with Savage Species & the appendices in the various Monster Manuals.
In addition to what Psion said (in case that isn't enough), each creature's respective Environments are diametrically opposed. I don't think there are any official planes out there that have both good- & evil- alignment traits. Plus the flavor text states that each type dwells on upper or lower planes, respectively. Hard to combine the two, outside of artificial manipulation (magical experimentation, rituals, etc.).

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.