Been testing Genesect in a Sun Team, and it's been working very well. I've been using a team stacking a lot of hazards which means that Genesect can easily rack up residual damage on incoming Pokemon and easily threaten them out with the prospect of a U-Turn, or appropriate Special move. A team which has Genesect / Forretress / Dugtrio means that you very easily gain momentum while being able to trap other weather inducers. This is super important on a Sun team, when Sun traditionally does not have the best matchup against other weather inducers, or other weathers in general.
As for the viability of common Genesect sets, it's easy to see that Scarf Genesect is the superior option, while Rock Polish / Focus Sash variants are still viable, and good at bluffing a Choice Item. As for defensive sets, there's really no need. Genesect has such a great offensive movepool it would be a shame to waste it. There are other bulky Steels such as Jirachi and Skarmory who play a much better defensive role than Genesect, while also getting access to hazards and recovery.
Expecting to see a rise in offensive teams using Volt Turn, or hazard stacking in general. Genesect benefits greatly from hazards, even if it is just a layer of Stealth Rock. I've found the best way to use Genesect, is to find good offensive partners to deal with its main checks / counters. Dugtrio for example is a great partner, trapping Ninetales, Heatran, Jirachi, Volcarona, Toxicroak, Terrakion, Tentacruel and more. It easily cleans the way for Genesect to sweep late game when all of its checks are gone, as nothing will appreciate a +1 Ice Beam / Thunderbolt / Bug Buzz coupled with hazards.