July 2019
Wattson is similiar to Caustic, she is good for defense, not offense. She doesn't offense or escape ability.
In your situation, you set up defense in close area, ask your team mate to crawl there, let them come to your term, until they give up or move on.
If they kill your team mate, simply wait it out until they move on.
Note:
There's reason people doesn't thrist, they want down enemy as bait so their mate team mate come in a rush, like 911 call, in panic emergency mode and blew up all the strategy out of the window , simply rush in and die easily in the process.
July 2019
I don't agree that Wattsons fences are useless. As mentioned before I think they just need to be tactically positioned to be effective, so the base cannot be shot.
In some scenarios this is easier said than done but then you just don't set it up there. Likewise to some legends the fences are not an obstacle (Wraith, Pathfinder etc) but then everything needs a counter. Going back to getting shot it's exactly the same as Caustics trap and if they are planted in the open they are shot just as easy, if not easier.
In regards to her ultimate you could argue it's not spectacular early/mid game but come end game and dealing with grenade spam it serves a purpose. That and the fact I've heard they are stackable so you could have 3 all charging your shields quicker makes it useful, not forgetting they charge instantly with the ultimate accelerant.
August 2020