Gengar was pretty devastating in the gen 7 version with its Cursed Body shenigans, but since this seems to be pick 3, it seems more manageable this time, since now with Cursed Body you can switch your mon out. I think Gengar could still have value in that it can get extra Metronome turns and have a win condition against the last mon, but I do wonder if its bulk problems will be more glaring when it has to face more mons, and it has actual Ghost competition now (mainly Dusknoir / Dusclops). The normal immunity and cursed body ARE still good however, to be clear!
Anyways, here's some stuff that was good last time. I should also note that, I feel like Pokemon generally prefer a lot of bulk investment unless its some sort of heavy hitter like Medicham! Yes, even something like Gengar is probably going to prefer bulk investment!
Clefable's access to Magic Guard is HUGE. Residual damage from status comes up a lot in this format, and being immune to that can really save your ass! It's also a damn good Life Orb user if you want that, but Leftovers and Rocky Helmet are good too!
Snorlax is pretty damn bulky, and is immune to poisoning, so it's usually a pretty good choice in this format! Rocky Helmet and Leftovers are good on it, but note that if you're willing to sacrifice some bulk, Choice Band Snorlax was no joke last time.
Like it's been mentioned before, Gengar was really nasty with Cursed Body. This is likely to be migitated with switching, but it still buys you time and can ruin last mons. Gengar can also actually run Black Sludge to free up Item slots, and the normal immunity is always nice.
I feel like this was overshadowed by Jirachi last time, but with that banned, Togekiss's Serene Grace and good bulk can let it BS some mons to death!
So you'd think Machamp's big thing would be No Guard... which yes, that's good! However, don't forget about Guts: status flies around a lot in Metronome cup, and Guts can let you potentially sweep with that! Just note though, Machamp is rather frail...
Blissey has crazy special bulk, so its always a reasonable choice. Now, you might be thinking "why not Chansey?" Chansey's issue is that it has basically no offensive output, while Blissey at least has a sorta usable Special Attack stat. Since this is 3v3 though, Chansey stalling stuff could hypothetically be useful though....
Since there are three new mons allowed that have potential, I should talk about em a bit!
Dusclops and Dusknoir were banned last time because of Pressure... which seemed silly because Pressure doesn't actually affect Metronome! Turns out we were wrong though, Pressure DOES work if Metronome targets them! So as a result... Dusknoir and Dusclops are likely to be top tier Pokemon!
Woah Prankster Metronome! I mean Sableye had it but that thing sucked! I can't remember if Dark-types are immune to Prankster Metronome or not, so that and the rare Indeedee might mean this thing gets benched a lot, so IDK about this thing yet.