Sleep clause is a thing in Stadium, Stadium 2, Colosseum, XD, and Battle Revolution. Sleep clause is not some wholly unofficial invention of Showdown.
Phasing is mandatory, suction cup is now good and argubly better than magic bounce
It's too bad Malamar, Octillery, and Cradily are it for Suction Cups, particularly since Malamar is 99% better off with Contrary.
Also, Haze resets stats, Psych Up steals stats, Topsy-Turvy inverts stats, KOing clears all their stat changes, and stat-downs are persistent so you can do stuff like Acid Spray them every time they Amnesia. Venom Drench in particular is actually useful here and is difficult to pull ahead of with your own stat-ups, particularly since its success implies you're also currently Poisoned. Toxic Spikes+Venom Drench might actually be viable in this meta.
It is, but I think this meta is trying to stay within the original mechanics of the game outside of the whole switching = passing thing.
It would also slightly distort Accupressure, making every possibility a 1/6 chance. (Unless the decision was "anytime it would roll Evasion, nothing happens", which is a different kind of distortion)
One thing that's occurred to me is that Agility is a lot better off in this meta. It can actually be worth spending a turn on it to then switch in something comparatively slow (Particularly something that can't normally boost its own Speed, like Malamar) that can take on whatever is in front of it, because the Speed boost is kept. Of course, Dragon Dance and Quiver Dance are pretty much always going to be more worthwhile, but something worth thinking about.
Moxie is also a little better. Sharpedo and Yanmega are slightly more appealing, since they can now pass their Speed Boost boosts like the other Speed Boosters.
U-Turn, Volt Switch, and Parting Shot are odd, because instead of being free damage on your switch they are potentially losing all your buffs, but conversely they can potentially escape hefty debuffs. Particularly relevant if Topsy-Turvy becomes standard.