Can I stop you for a second there, Ace? I know people are comparing Victini with DPP Garchomp (or was it Salamence? Damn, I just read about DPP Salamence and I got them mixed up) and I can't really comment on that because I didn't play competitively back then, however I'm pretty sure I can say a couple of things.
I was refraining from posting here because there's just too many things being discussed at once, but I'm gonna have to do it anyway. You're saying Victini's versatility is such that you can lose a Poke without misplaying or without being outplayed, and I find that hard to believe. Maybe it's because of the way I build my teams. But, if for example (and I'm using Pokes from the last team I used extensively) you switched Slowbro into Victini, it showed Blue Flare and LO recoil (or just Blue Flare but without it being Specs damage, it's the same for this part), and you left it in even though you had Scarf Flygon on the wings, and Slowbro died to a Thunder, I'd call that a misplay in your part because you know Victini /can/ have that move, even if it almost never uses it. If, on the other hand, it used Thunder outright and left your Slowbro near-dead or dead (with Expert Belt, it's a coinflip after SR), I'd consider that getting outplayed. I might be giving those terms a wider meaning, though.
I can give room to koko's point of it being able to wallbreak to a point where stuff are just so weak other Pokes can pick up the pieces, though. That's Victini's job, and it's one of the biggest reasons defensive teams have to keep their eyes open against it. Luckily we have Team Preview, so if like, you left your Qwilfish to die even with the knowledge your opponent had Scarf Mienshao, there's a certain degree of responsibility on your part. I dunno, maybe it's the way I teambuild (for example, I'd tried making a defensive Mismagius team and ended up with Qwilfish, Rhyperior, Lefties Offensive Snorlax, and Umbreon, and Mismagius had 216 Speed EVs with a Timid nature, so lol).
I won't be vouching to have Protect in every Pokemon to scout if Victini has the right move to kill you or anything of the sort, because that would be taking things too far. However, if you have the knowledge of what moves Victini might run (not what is common on the ladder, its possible moves), you should technically be able to handle it after that first move. And if it Thunders your Slowbro in the first turn, then applaud your opponent for outplaying you (even if it was an unnecessary risk). That's what I think and it's the biggest reason I can't put it to the level of Kingdra or Chandelure as for offensive threats, because in those cases, if you don't have the right Poke to check every set (Slowking and Ice Beam Empoleon for the former, Snorlax and lol Houndoom for the latter), you can still play around them but you're at a much bigger risk before you know the set (and also Kingdra can technically wallbreak and sweep at the same time, not that it matters). In Victini's case, as long as you don't leave in Rhyperior against a Lead Tini, you can possibly beat it if you don't get outplayed. And if you do, better luck next time, right? I'm not implying anything about Kingdra or Chandelure's place in the tier, considering I'd posted in both threads saying why I didn't think they deserved to be banned at the time. I've also had to play around both for a huge amount of matches when I was trying to get reqs in Suspect ladder (I ran RT Hail), and like 90% of the time was victorius, but mostly because people misplayed with them (I mean, if you have Specs Chandelure that destroys everything that switches in, why leave it to get rk'd after getting the first kill? lol).
Maybe I'm being too minimalistic reductionist? It's certainly a possibility. I might be having a really closeminded thought of the subject, considering some teams' only thing faster than 328 Speed is Scarf Mienshao. So you can't really expect to succeed against all Victini. I'm not gonna be the judge of other people's teambuilding, but there are certainly many options to choose from to have at least one thing that can switch into a particular move and not have to come in on the revenge kill! Because that certainly is a good way of pressuring the opponent as well as scouting for a move. Not that I'm suggesting you go from Slowbro to Crobat expecting Grass Knot, rather that you make the safest plays while you're familiarizing yourself with the opposing player.
Note that I'm not talking from my experience on the ladder, because I've seen plenty of times that people left their Rhyperior in on a Victini that had only revealed that it wasn't Banded/Specs'd. Victini is as scary as you make it out to be when you face it, and I can only see a cute little rodent when I do.
OK three people posted while I was writing this, lol. I'm gonna have to organize my thoughts when I'm more awake, so this will probably get cut down tomorrow (so people will actually read it!). The point was mainly that I didn't really see what Ace was saying, and that if there's one set that's scary when you don't have the right Poke (Slowbro, Rhyperior, Swampert or defensive Arcanine), it's the CB set for sure. Of course Slowbro takes a lot from Bolt Strike, and Rhype and Swampert might fear Grass Knot if you're playing Kitten Milk, but luckily the former has Regenerator and GK isn't always the best option on BandTini, so I'm not gonna have to lower it to merely Arcanine. Once I know it isn't Banded I'm certain I won't have to suffer so much switching in.