I haven't been to this board in a while, but since posting on the PDGA DISCussion is now limited to members, I figure new players will be turning increasingly to this site for advice. I'm here to offer a little help with the sidearm shot. Although some of what follows will conflict with what Blake says, I hold him, his knowledge, and his contributions to the sport in the highest regard.
There is a lot of decent, but not complete, advice online about throwing sidearm. In particular, there are two misconceptions that I think hinder people from developing the shot to its potential. They are, in no particular order:
1. Throwing sidearm for power will ruin your elbow.
Not if your technique is good. I experimented with the Stokely method, and yes, it caused me considerable elbow pain. I think the culprit is the advice, "lead with your elbow". When I throw a good sidearm, my elbow doesn't do much work at all. It basically stays in position, tucked in tight, fully extended, or somewhere in between, depending on the throw. Yes, your elbow should lead your hand/disc, but it follows shoulders, chest, and hips, even on a low-power shot.
And then, and this is crucial, you must follow through. It's easy to tell if you're doing this right. If you are, you'll throw smooth, powerful shots. If you're not following through, you'll throw crappy shots that hurt your elbow.
2. Sidearm power comes from the arm.
This is dead wrong, and probably contributes to arm problems. Like every other kind of throw ever, sidearm power comes from effectively harnessing a weight shift. Think of it like a medieval trebuchet: A big, slow weight comes down, pulling a long arm with a sling attached to it up. With the leverage provided by the arm, that slow weight shift becomes a whipping action fast enough to launch a 500-lb. rock a quarter mile.
You can throw a 350-foot sidearm with no arm effort at all if your body mechanics are right. The arm is sort of a turbocharger – a boost you can give your throw after everything else works out properly. I need the extra arm effort to get out to 400', and I find it makes shorter shots a little more precise, but it's by no means the main power source of the throw.
I hope this helps people, at least a little. Someday I may get around to posting some video of myself, but otherwise, you're on your own as far as implementing this advice. The most important thing to remember is that if you want to develop a good sidearm, you have to throw it constantly, and focus on improving it. Reps aren't enough. You need to pay close attention to what you're doing and how it affects the flight of the disc.
Good luck.

