While Sun Stall is a very good archetype (I have used it to a lot of success in the past), I am not sure if it is the right playstyle for a CCAT. I do think that alexwolf covered this pretty thoroughly in his post, but Sun Stall is really limited in its Pokemon choices. While there is some room for creativity, there isn't much. Almost all Sun Stalls are made out of a pool of like 9 Pokemon, and while it may be a very strong playstyle, I don't think that type of limitation would be good for a CCAT.
On a similar vein I am also some what skeptical of Hail Stall as most successful Hail Stall's are also made out of a pool of like 9-10 Pokemon. Don't get me wrong, I am not saying that these aren't good archetypes, I just feel like if we choose them then most of our team will already be "chosen" and there will be little room for actual creativity and innovation.