Hammer Titans are about as easy to take down as a Blade dancer. I.E. Throw a nade, get a headshot or two, hide behind cover and when they run at you melee them and it's GG. Sometimes you die, more often you both die, and most often they die. PvP is all about reading the enemy. Are they CQB only? Get distance and shoot. Are they long range only? Close distance and melee. Use the map to your advantage, use their class weaknesses to your advantage, and learn your own class.