Yeah, the unusal pokes were due to mewten's stall team--actually quite effective.
In addition, genesect is one of the best anti-metagame pokes in general--rock polish sets can be used by non-sand teams to beat excadrill and plow through many sand teams, and scarfed u-turners are amazing in countering both sand and rain teams when combined with volt switchers, especially due to genesect's constant prediction threat of actually using an attacking move, which can KO many weather abusers.
About bronzong vs. gliscor: while gliscor is a good counter for excadrill, it is hit neutrally by frustration and rock slide, allowing exca to KO it much more readily. Furthermore, bronzong also has a dragon resistance, so it can double as a dragonite/garchomp check if the fire weakness is covered.
Surprised jellicent isn't used more--it is basically as perfect a keldeo counter as exists, and can actually check genesect too (+1 thunderbolt fails to 2HKO through lefties).