So how to do it? What are the conditions to it?

I know for sure that a templar storms if it gets shot and has the psi storm researched. Dark Archon uses mealstorm if attacked, and feedback if a energy-based unit attacks it.

Optical flare comes when the medic is attack by someone with more than 81 hp.

How about mind control?

Here you are:
http://web.archive.org/web/20050412044703/http://www.staredit.net/index.php?tutorial=175
Check the lower part to find Mind Control