During Ash's Ultimate ability she is not CC Immune, Makoa can Dredge Anchor her out of her area and Bomb King can stun her with Grumpy Bomb. If she has the Battering Ram legendary she will use this to escape the stun and therefore be out of the area!
Ash's shield is small compared to the other tank character's shields (Height-Wise). If you can, try to get above her shield or go around it to attack her.
Ash's ult is powerfull and easy to counter(all cc abilities) but you also can make her not even use it, like hook with makoa , torvalds ult , Jennos grip, Shalin's and Cassie's rmb arrow can block her 'Ult jump' or move her ult to other place