When you find any illusions, simply destroy them with Defiance. This makes tracking down the real Ying and killing her much easier, as she will have no escape options, and no healing source.

When against a team with a Androxus who pressures you a lot, place an illusion behind a tank just as a precaution, if you get cornered by him in a fight, simply teleporting to that illusion will save you, as Androxus can only deal with single targets