I came up with this strategy near around when team covenant was doing its first x-wing tournament and I wanted to test out the theories behind it. I thought about bumping and losing actions, which is a common Imperial tactic, and I wanted to use a counter tactic of not needing actions. The YT I chose as a base as I found the ship to be good with its firing arc and pilot abilities. I also tried to think of a defensive play that would make it easier for maneuvering and realized that two ships could lock together and thus not have to move.
I played 2 games with Theorist and he ran 4 X's with shields, and 4 X's and one was Biggs. The YT fortress build beat both, with the second game being closer (and it was the squad Theorist brought after having just lost against the YT and he now knew of the strategy being deployed and was asked to try to beat it.)
After seeing the success I really didn't wan't to release this strategy as it wasn't really dogfighting and is more of a game play nullifier because it forces your opponent to come after you as you do nothing but exploit the rules. It isn't in the spirit of the game so I haven't pushed its knowledge until now, as I will explain later.
First let me show you what this build is.
How to build the YT- Fortress build
Han solo with Determination, Gunner
Chewie with DTF, Gunner, (and M.F. or not) for 99 (100pts)
The idea was to fly the two ships and lock them together near the bottom edge of the play area. The ships would take on Han as the high priority target and focus fire. Chewie will pull off crits and effectively share shields/hull with Han and keep him alive longer. Any hit on Han would be discarded (if it was a pilot crit) or pulled over to Chewie to have no effect. Both ships would target one ship and take it out and then work on the next ship.

The advantage of stopping forces your opponent to fly at you for a turn or two and then have to turn away. The YT's proximity to the edge prevents a K-turn and firing arcs are hard to keep on target. They strafe and wound one YT and then have to turn back, and target the other, spreading their fire over both ships and reducing their hull near the same time.
How to Defeat the YT- Fortress Build
If you see your opponent line up 2 YT's facing each other from opposite corners, here is what I suggest you do:
Slow play your first move to see if the YT's will in fact move straight towards one another. If they do they might use this strategy. If you see them moving together and lock you must move to the side that Chewie is on. Fly down the edge and turn from the far edge in as slow as you can go. Target Chewie first. You are trying to keep your arcs on Chewie as much as possible. Fly just above and strafe and then K turn back after you have passed Chewie and continue to attack Chewie only!
Targeting Chewie first will stop the DTF advantage and put hits on one target. Once Chewie is destroyed, Han will have to fly free and then the chasing him down becomes the difficult part.
If Han is swapped for Lando in an alternate build, still target Chewie first.
I firmly believe that this build should not be used in a tournament setting as it kills the enjoyment of the game. A Lambda version and other strategies of stopping ships and forcing a fortress like ship clump that an opponent has to try to solve have appeared so I think it is time to speak out about this way of playing the game. It may be something that starts to appear in actual tournament games so I'm hoping to spoil the strategy before it gets too widespread.
I will finish with saying that using this strategy fails the "fly casual" spirit of the game so be prepared to be called out on that if you use it in a tournament setting.