edit: sorry if this post seemed a bit, well, self mastrabatory
Put the lotion away, brah. No, jk. But on a more serious note in general I've been kinda holding back on my opinion of Victini...and to an extent I'm still kinda reserved on it, mostly neutral. Imo the most ridiculous set to me has always been the Choice Band set, because as you stated, the excellent wallbreaking potential it has to spam a team to death with one move. But at the same time, as for the other sets, literally..just assume Victini has Grass Knot. Rock with me here for a minute. Just play as if you're expecting Victini to carry Grass Knot (If it's not the CB set, it most likely does carry the move...Otherwise, one would be shaking their head.) and just suddenly realize all those times you let your Rhyperior die were times you could have gotten around it a bit. Far as scouting the set out goes, I guess I can apply some personal experience. Like people say Slowbro's a weak switch-in to the Banded set because CB Bolt Strike can 2HKO the poor guy. See the thing is, even if the guy was actually using a mixed set with Charcoal/Expert Belt or something and you switched it in on Bolt Strike, the damage output itself is enough to tell you what you're dealing with here.
So following this scenario, you realize this douche is 2HKO'ing your Slowbro with Bolt Strike, doing no less than 61% to you. Okay, he's banded. Time to switch into my Ground-type/Electric resist and seize the momentum, while giving Slowbro some Regenerator health to come back in later on this thing! And now I know he's Choice Banded, even if he was "that guy" who ran Grass Knot for the maximum surprise factor, Rhyperior/Swampert (Believe it or not, Swampert actually takes this better) could survive it and do whatever afterward, so long as I'm not switching directly in. Basically Band Victin's big issue is that if any of its actual checks that get decimated by Grass Knot are on the opponent's team, in general it's gonna be relying on its teammates to remove it before it can actually get to the fun part of carelessly spamming V-Create. And then you gotta watch your U-Turn intake, as Stealth Rock can add up quite a bit. Not gonna factor that in here because offensive pressure can sometimes guarantee no hazards for a decent period of a match, but it's still pretty important to note.
Other issue is that every time Band Victini gets a kill, he's gotta switch out. V-Create makes you susceptible to being revenge killed significantly easily, and even a single misprediction can give away your set and make it that much harder to effectively maintain its effect against your opponent. See, offensive pressure can work two ways here. But once again bear in mind, this is all hypothetical, and I'm just kinda highlighting some of the flaws of this set.
As for the mixed set with Expert Belt/Charcoal, you're kinda shut down by Snorlax, Umbreon, and Porygon2, the big special walls of the tier. Obviously cause of the lack of knowledge to which set you could be using, this set can get some surprises on the opponent. But those Pokemon still take pittance from this set's output, even if you run Focus Blast...For example, Lefties Snorlax is only 3HKO'd, meaning it doesn't even care if you nail it on the switch; you just gave it several reasons to use Pursuit against you, regardless of what you do. Umbreon has less than a 2% chance of being 2HKO'd by V-Create if you only run 4 Atk and a +Speed nature...And provided you manage to pull that off, a simple Protect can put it out of 2HKO range, with the low output now revealing "Hey this guy's not banded, Umbreon's got nothing to worry about".
And there's still general ways to keep Victini in check such as Pursuit/Sucker Punch, Stealth Rock, Spikes, Aqua Jet, Sleep/Paralysis, etc. etc. And once again what all I'm saying is still hypothetical. You may not have the Pokemon I mentioned here to ease the difficulty of dealing with Victini, or the situation may play differently. Or the Victini gets a crit on you and your game plan goes out the window. Or maybe your opponent is a super genius capable of reading your mind and utilizing clever double switches and going for the unexpected play to catch you off-guard and make you want to ban this thing with all your might. Whatever it may be, just focus on what I'm trying to emphasize with all these paragraphs:
tl;dr, Victini is still able to be kept in check, and the two main sets it uses can be scouted based on their damage output from the initial jump; by using a bit of caution and expecting the "unexpected" Grass Knot, one should be able to prepare for Victini a bit more effectively and thus deal with it as such. Overall I'm still neutral on the thing in general. The Choice Band set is a pain to switch into and the scenario and weaknesses I described above don't take away from that. Just some food for thought...