I recently heard this described in another thread and it got me thinking.
First let me define the term. A Shark has not had major changes in evolution for billions of years. The slight changes have slowly made it more an more perfect for its biological niche.
A Shark list is a list that a player has been been playing and refining for a long time. They came up with the basic idea a while ago and have been doing two things since then. One making small tweeks, and two practicing with it a lot.
I first encountered one of these lists are a tournament about a year ago. It was a Chewy and Lando double Falcon list. It smashed its way through most of the tournament. When I faced it, I was trounced. It wasn't because the ships were OP but because the player had found a good list, tweaked it into its best possible version of itself and then really knew how to fly it.
That tournament left a sour taste in my mouth, but when I realized what he had done I couldn't really blamed him.
I am a casual player. I don't get a ton of time to play. I spent about 10 times more time on the forums talking about than I get to actually play. When I do, my primary motivation is to have fun. I almost always try something new each time. I don't think it is reasonable to expect me to be able to compete consistently with players who simply play that much more competitively than I do. In any game of skill the more committed players (committed to winning) should win. I guess it is a good thing that they do in X-wing.
Even so, I would still like to beat them.