Outsiders are barred from entering the plane, as such, schools of magic that summon monsters and creatures that are outsiders fail to work in the usual sense. They summon what the summoner thinks or believes a creature to be. They are summoned through the stagnant residual energy surrounding them, as such there are no alignment restrictions while summoning because the summons are “created” for the purpose and not an actual creature. Eidolons fall under special rules in this world, they aren’t really summoned more created when the summoner manifests them, they are essential part of the summoner’s soul.
Outsider Body Hopping
Outsiders cannot enter the plane, as such they’ve devised methods to enter it by taking a mortal’s body or sending emissaries with their power to do their bidding. In essence this makes it so Outsiders are unheard of, no one knows about them anymore, no one remembers them existing. Although its been “25 years” since people have come through the portal, not many people seem to remember them.