| Threeshades |
At this time it's up to your GM's discretion. I see the unchained eidolon's evolution list as an update to those evolutions on it, but not as the complete list of evolutions available, any other evolutions I allow as is.
Considering the nature of Unchained I have a feeling there might not be an official ruling on it.
| Dragonchess Player |
Adventure Path Charter Subscriber; Pathfinder Rulebook, Starfinder Adventure Path, Starfinder Roleplaying Game, Starfinder Society Subscriber
It looks like Unchained only updated/reprinted the evolutions in the APG; the biggest change seems to be Pounce becoming a 3 point evolution with a minimum summoner level of 7th. All of the additional evolutions in Ultimate Magic are probably still allowable with GM approval.
For PFS, I'm not sure.