Jenos can 1v1 weaker enemies very well, he can pump out some decent damage and then use his Void Grip to allow his teammates to gank you. If you are able to, try to continually shoulder peak him so that he can't Void Grip you, or take a teammate.
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.