If I use Aegislash's "Ticking Knock Out" attack but my opponent moves the Defending Pokemon to the bench, on my next turn if I bring that Pokemon active and damage it or if I damage it on the bench is it knocked out?
Only if you do enough damage to meet or exceed that Pokemon's remaining HP. The effect of "Ticking Knock Out" is on the Defending Pokemon and is cleared when it moves to the bench, so you would have to knock it out by normal means rather than by simply doing any amount of damage to it.
Ticking Knock Out