The Yoshi, the problem is that that discussion is too specific, plus "best ability" is too hard to pinpoint. You have to look at what we have, and most of the Pokemon that have these "amazing abilities" also have amazing stats and typing, like Tyranitar and Reuniclus. It would just come down to "weather ability, ability to block weather, and ability to abuse weather", and that's not really a good topic to discuss imo. I'd be better off discussing what weather is currently the best to use.