Focus sash genesect is actually a very viable and underrated set. It obviously requires rapid spin support to be used to its full effectiveness, but it gives genesect the ability to act as a last-ditch stop to a sweeper, which is especially useful since genesect can pretty much KO any set-upper once they've taken a little damage. Sashsect also beats other genesects, can escape from chandelure (after taking a hit, surviving with sash, and u-turning, something occasect cannot do), and gets that great coverage.
Another set that, although I agree it is generally inferior, has some nice uses is the flame charge set. The big difference between genesect and something like heatran using flame charge is that, despite its low base power, genesect can actually do some decent damage with flame charge due to its high base attack. This allows genesect to run a set with fire/ice/electric/bug coverage (or even throwing in a STAB like flash cannon, which can catch ttar) while still boosting its speed and not being restrained to one move, a combination that can quite easily sweep unprepared teams (especially since so many of them simply rely on resisting genesect's choice-locked attack to switch to a resist). Overall, probably not as good as genesect's other sets, but it's more effective than people give it credit for.