I see a lot of discussion about weather when it comes to VGC. However, most of it seems to revolve around specific Pokemon, their weather effects, and moves / abilities that take advantage of it. It is a given that in a VGC match, there will be a weather effect for most of it - most likely Hail or Rain. However, I don't believe that running a "Rain" or "Hail" team is the way to do it.
Looking at the most successful VGC teams, they have around two - sometimes three - weather-inducing Pokemon. The most common being Abomasnow, Kyogre, and Groudon.
Weather control is the most important part of this metagame. If you are too reliant on weather effects, you will lose. I'm not saying don't put Thunder and Blizzard on things - on the contrary, I'd stick 'em on everything - but I wouldn't bet on always being able to use them at whim. All it takes is a switch-in to kill it.
How are you using weather at VGC and how have you seen it used?