I cannot possibly write the level of detail I can articulate on this as I could write a small book on the subject.
Point number one to note, is that different styles will be effective for different Armwrestlers depending on their own genetic make up and the physical tools at their disposal ie. Variables to consider are 1.) Comparative Length of Forearm 2.) height of both athletes, 3.) Inherent speed and that of your opponent, 4.) size of hand, 5.) strength of rotators BOTH directions, 6.) whether you want to stop your opponents Top Roll with a counter Top Roll ie. in order to facilitate your own counter Top Roll or in order to Hook or Press once the match stops, etc. etc. etc. the list really would go on and on BUT before you start to waste time training what might work for Me or Steve or Paul, Andy Wise or whoever you need to take a long considered look at yourself in the Mirror and realize what weapons you have at your disposal as ultimately you need to build of solid fountations if you want the structure to be solid.
Hand & Wrist position and the position of your Elbow on the pad prior to the start of the match can unlock a miriad of opportunities against opponents of various physical specs. however is the key is to irst know what you really want to achieve, then and only then you can disect a technique comprehensively.