Unchained Eidolon vs Incorporeal

[Ilyanwinn]

Hi all,
i'm playing an unchained summoner. I have a question for all of you: how can i make full dmg to incorporeal mobs with my unchained eidolon?

[Melkiador]

Ghost Touch on an amulet of mighty fists may be the best solution for most levels. There’s a level 15 evolution for incorporeal, but I assume that’s not an option for you.

[Java Man]

A radiant or void subtype eidolon gets ghost touch at 4th level.

[avr]

There's spells if you can get a suitable spellcaster on your side. Ghostbane dirge, I'm sure there's others.