When in a battle you have no control over (ie. arena or Auto button), Chloe and Christina use the wrong attacks.
Chloe will constantly Drum Dance to heal herself ASAP when she is at full HP and using the Wild Call skill set, and when Christina is using the Justice skill set she doesn't use Righteous Strike at all, she instead uses the normal "generic" attack that costs 0 SP, then uses the more costly "Justice" attack.
The Chloe non-attack Drum Dance is quite annoying, but Christina not using Righteous Strike is just inconsistant compared to any other hero. They all try to use their strongest attack first except for her.