What outsider sub-types are allowed when creating a weapon with Bane property? The actual weapon property itself simply says "pick one subtype." However, in my opinion picking extraplanar as the subtype is at the very least cheesy, if not illegal. Similarly, choosing incorporeal or native also significantly broadens the scope of Bane. Has there been any clarification on this?
In particular, I am curious if something like an Animate Dream can even be targeted by a Bane effect, as its only subtypes are extraplanar and incorporeal.
I believe only the subtypes that say "X are a race of Y-aligned outsiders, native to the plane of Z" are true outsider types (angels, demons, proteans, etc.).
Both the extraplanar and incorporeal subtypes can be applied to creatures other than outsiders (to creatures off their home plane and most popularly undead, respectively), and as such are not "outsider types".
"Good", "Evil", "Chaotic", and "Lawful", however, are outsider subtypes and valid choices for Bane.
Edit: missed native outsiders. They are a valid choice for Bane, but aren't much more likely to be in a campaign than a type of outsider such as demons, however, and it's usually not as powerful as it seems.
The 3.5 edition bane list included only four elemental subtypes (which were much rarer for outsiders as actual elementals were separate type) and four alignment subtypes. I'd say that "racial" outsider subtypes (aeon, aether, agathions, angels, archont, asura, azata, daemons, demodand, demons, devils, divs, inevitable, kami, kytons, manasaputra, oni, proteans, psychopomp, qlippoths, rakshasa, sahkil, etc.) and "elemental" subtype (which was a separate type in 3.5) are suitable choice as would probably be "native" subtype. I would not allow for extraplanar (too many creatures with that subtype to be a meaningful restriction). Outsider (incorporeal) could work - they are not very popular now so it would be probably subpar choice, actually.
EDIT: Note that racial outsider subtypes are already subpar choice to alignment choices - because an evil outsider bane works against asuras, daemons, demodands, demons, devils, divs, kytons, qlippoths, and sahkil, plus more outsiders with evil subtype that have no racial subtype. Other alignment subtypes have less outsider races associated but still multiple ones per alignment.