The Gryvains basically force you to use tease attacks if you are playing Mercenary. I tried with a Tech Specialist earlier and you can get crits with the Scoped Pistol and hit easier so it is possible. My Merc just cannot beat them through attacks though and the character I was going for was not going to use tease attacks. I just find it really annoying that you pretty much have to use them. Corruption of Champions doesn't have anything like that.