Genesect GX seems alright, but I feel like it's really frail.
Metal doesn't really have fantastic energy acceleration right now (Magnezone is clunky, and then Registeel is kind of the only other solution they have without Max Elixir post-rotation), and even if you double stack choice bands and Genesect GX becomes a large slice of the meta, people will just use a single field blower to knock them both off. Once Puzzle of Time rotates, there aren't exactly a lot of ways you can recover items from the discard pile, so once you lose double choice band and get KO'd, you don't have many options for recovery and retaking momentum.
At this point it kind of just becomes a decent solution to countering fairy types, but even if that's what you want to use it for, Stakataka GX is better in every way at that job while offering some defense for Beast Box in non-fairy match ups at the same time. With access to Beast Ring as well, Stakataka GX can get going in 1 turn and takes 2 hit KOs just the same. The GX attack on Stakataka GX has a higher ceiling as well. At 3 prizes taken it's already outgunning Genesect GX.
Like seriously, Stakataka GX with 4x frying pans is going to become a problem that really tests the endurance of energy discarding decks like UNGX that need precise set ups to maintain momentum.
