Come to think of it, I think a better way of dealing with subtypes for outsiders would be to divide them into "races" rather than (mostly) alignment-based subtypes. Some races would be:
Devil
Demon
Yugoloth
Guardinal
Eladrin
Aasimon
Archon
Rilmani
Formian
Modron
Slaad
Genie
Mephit
Elemental Beast (Arrowhawk, Xorn, Tojanida, Salamander)
Planar Beast (Howler, Shadow Mastiff, Hell Hound, Couatl...)
... and a few more. Some of these categories might be significantly smaller than others, but I don't think that would be any more of a problem than Humanoid (gnoll) only applying to one creature and Humanoid (goblinoid) applying to at least three.
Devil
Demon
Yugoloth
Guardinal
Eladrin
Aasimon
Archon
Rilmani
Formian
Modron
Slaad
Genie
Mephit
Elemental Beast (Arrowhawk, Xorn, Tojanida, Salamander)
Planar Beast (Howler, Shadow Mastiff, Hell Hound, Couatl...)
... and a few more. Some of these categories might be significantly smaller than others, but I don't think that would be any more of a problem than Humanoid (gnoll) only applying to one creature and Humanoid (goblinoid) applying to at least three.