How do I give an enemy a "Counter-attack"?
Counter-attacks, a recent addition to the engine, can be assigned to enemies in the enemy "Attacks" subeditor. There are two styles: counter-attacks to attacks of a certain element, and counter-attacks against attacks that target a specific one of the enemy's stats. Since you can currently use up to 64 different elements, it is usual to use special elements for the purposes of counter-attacks, such as an "attacks that anger Fluffy-Mu" element.
Note that the "CTR" stat has nothing to do with counter attacks! It is in fact totally unused.