Originally Posted by flink

I've got confirmation that the equipement affect helper squad.

This is a test using Yuki Yanagi and Heliconia as a helper squad:
When used by an ally,
Lv1 Yuki (450 ATK) does ~200 damage,
Lv1 Heliconia (440 ATK) with a ring+10 LvMax (+1507 ATK) does ~700 damage.

Good to know that the girls blinged out with max level +10s actually makes a difference. Thanks for testing it out.