Tales of Vesperia

Nan has an attack that will get her weapon stuck and Tison has an attack as well that gets his hands stuck. When they perform these, Nan's I think is Rending Strike and Tison's Dragon Maw, avoid the attacks and quickly rush in and hit them to knock them over. This must be done for both of them, so focus on one (mine was Nan first) and kill them off after, then get the other.

You need to use an attack on both Nan and Tison after they have used a certain attack and they will fall over. For both, I personally used Yuri's Azure Edge (Azure Storm works too), because it's a ranged attack.

The attack for Tison has a large yellow serpent erupting from the ground. For Nan, it's a short range attack where some rocks strike from the ground. Avoid these attacks as best as possible then hit them quickly afterward when they're vulnerable.

If you're having trouble with your teammates interrupted Nan or Tison too much for the attack to appear, try changing the strategy for everyone else to "Different enemy" and they'll only attack whoever you're not targeting.