There aren't any popular metadecks that use Victini-EX. Rayeels used to play Victini-EX, but most lists dropped it once Kyurem PLF came out. If Virizion/Genesect truly becomes popular, then I expect lists to start to include it more.
But honestly, Virizion/Genesect isn't a deck to worry about in the first place. It takes them 2+ turns to fully set up a Gensect on their bench, and by this time you could have a Kyurem + 3 Deoxys + Silver Bangle set up to OHKO them, or a Blastoise fully set up with a BK-ex in play. There's no way it's going to be Tier 1, so there's no reason to worry about Victini-EX.