VERY Preliminary idea!
Another option for ultimate is "For each creature you control, put a token that is a copy of that creature onto the battlefield."
I have other ideas for the other abilities as well as I'm not 100% happy with copying Elspeth, Knight-Errant's +1.

+1: Target creature you control gets +1/+1 and gains Vigilance UEoT. ???
-2: Put a 2/2 white Knight creature token with Vigilance (or First Strike] onto the battlefield ???

Again, these are very early ideas, any assistance/input would be appreciated.
(Oh, BTW: This would be for my M-Core set as the White Planeswalker).

Considering the fact that both current Elspeths creature 1/1 soldier tokens, having the third incarnation makes logical, if not innovative, sense. In this version, though, the second ability feels somewhat green (though it does overlap with white, I suppose). Her ultimate, in the mockup, is so like doubling season that I can't help but think it feels green, and her ultimate in your comment is very blue. They basically feel weird on a mono-white planeswalker.

I was trying to carry over her "love" of token creatures in anew but familiar way for her - hence the half of doubling season as an ultimate on card & alternate "copy everything you control".
But then, this was just very early thoughts on possibilities, I'll be putting a lot of work into finding a combination of abilities that feels right.

I can understand the initial feeling of wrong-colourness, I was considering limiting it to Soldier and/or Knight creatures to make it more white, but then it became too linear/parasitic.

The second ability is pretty much Ajani Goldmane's second ability, so that seems fine :)

Changed the ultimate to a more white oriented version of the variant ultimate already mentioned. Slightly less wordy and better for that army feel.