Shaman's Wind Spirit (and other non-core elemental forms)

[Brew Bird]

The "Wind" Shaman Spirit's True Spirit ability says the following:

Shaman wrote:

Elemental Form (Su): As a standard action, the shaman assumes the form of a Huge (or smaller) lightning elemental, as per elemental body IV, with a duration of 1 hour per level. The shaman can use this ability once per day.

I assume this is supposed to be air elemental, but this isn't the only ability so far to mention an alternate form of Elemental Body. The Season Keeper Druid from People of The Stars mentions using wild shape to take an Ice Elemental form.

Are there rules out there for elemental polymorphs other than the four in Bestiary 1? Or any guidelines on how to figure out the ability score adjustments and abilities you should get?

[Cussune]

It's a good FAQ question. There hasn't been anything that I can see, but I would houserule by basing stats on the closest core elemental and giving whatever special non-"mastery" abilities the elemental has. So for the lightning elemental, EB4's air elemental with Spark Leap instead of whirlwind. The ice elemental I'd compare to the water elemental, but it gets more traits than the others. While I'd be fine with giving all of them, it would probably be closer with the rules concept to just give them one, most likely Ice Glide.