What rig setup do people use to catch those 15lbs+ Rainbow Trout?

[bo1xdream]

Do people intentionally go for the bigs ones using a bigger rig setup or can they be cause on 4lbs test line?

[Steve Carson]

The lake record rainbow of 22 pounds was caught on 2-pound test line, and also last year's biggest fish [20 pounds] was also caught on 2-pound line.
The top priority is "get the bite", or the fish can't be landed in the first place.
After that, its up to the individual's angling skill, how well the knots were tied, and of course a bit of luck.
BTW, the number one reason big fish get away is not having a big enough net!