Gee i hope that darkrai doesn't influence the council to start talks on sleep!?!?!?
Forshadowing ensues.
I don't know if you posted this here because of the discussions going on in SV OU, but this is probably not going to happen.
In ND, many offensive threats or walls that you'd think could viably use sleep aren't really as good as you'd think or would prefer to use a lot of other options. I'll take a few Pokemon from the thread this discussion was happening in within the SV OU forum:

- Admittedly, Darkrai is probably the strongest abuser of sleep as a whole (surprise, surprise); many would presume it to be even better here due to Z-Hypnosis forcing uncomfortable situations against defensive checks and attempting to power through teams (if the move lands). However, there's huge opportunity cost irt dropping a coverage move in Focus Blast or Sludge Bomb in this tier; if you lack Focus Blast, you do much worse into Fighting-weak / neutral Dark resists or other targets like Mega Tyranitar, Heatran, and Mega Mawile, among others, while dropping Sludge Bomb renders you useless against stuff like Clefable. This is not to mention that Hypnosis is
still Hypnosis; you are banking on the fact that you actually land the move to pull anything off, which is the reason that not many players have turned to this set, and have instead been using more consistent options like Nasty Plot + 3 attacks or Choice Specs.

- Putting these together for their similar qualities; both are able to (kinda) check Ogerpon-W and pivot into certain physical attackers + spread status with paralysis, poison, and of course, sleep. However. both Amoonguss and Tangrowth have more flaws than others of their nature and haven't seen consistent tournament usage at all (Amoonguss absolutely hates Gliscor being everywhere and is a Grass-type that can't actually check Ground-types that reliably, while Tangrowth doesn't actually have notable flaws but is just generally less used for something like Ferrothorn for its ability to spread item removal / status / pivot into Ogerpon-W, etc.). As such, trying to justify a sleep ban off the basis of these Pokemon existing is a paper argument imo.

- HO feels just okay rn and Aurora Veil offense is similar in that regard; I don't think sleep really plays a huge role in why you'd pick Veil over other forms of HO, since hazards are equally as valuable and easier to keep up with how much pressure teams like these exert (and also this thing has basically nothing else to run really lol). Its typing isn't really geared towards fishing for Hypnosis either because of the prevalence of stuff like Mega Scizor, Garganacl, Iron Crown, etc. Don't think this would really play a huge factor in consideration of a sleep ban either.
Unrelated, but I'd appreciate it if we stopped posting one-liners too.