What Bosses can be Pet Attacked?

[Calvin]

i know orc can.. but there's a lot that cant be targetted by pets :S

[The Silvertiger]

Only one I've seen is grim. You just have to spam it sometimes. On grim, you have to have it guard you and take some damage. I like to park it right on top so it never loses agro.

[Otim O'Connel]

All can be attacked. The effect pet refuses to attack is called scary. But, set pet to guard get aggro from boss then move out of range pet will defend.