The best advice I can give you is try to predict when it will switch in. Tricking a Choice Scarf onto it is likely going to reduce its threat level significantly, as well as Hisuian Samurott's Ceaseless Edge doing tons to it.
Barra's faster in and out of rain, notably being able to outspeed and take a bite out of Flutter Mane and Spectrier, doesn't get worn down with Wave Crash (and Float can't 2HKO "water resists" like Toxapex anyways, while Barra can gamble and hit it with Psychic Fangs), and access to Close combat makes it better than the sea otter.
Neko already basically answered it, but I'll give my advice. The reason Floatzel was considered better than Barraskewda in OU was because it could Tera Water to 2HKO supposed checks with Wave Crash. However, in a tera-banned format, Barraskewda has far more coverage, being able to hit Fighting-types and Toxapex with Psychic Fangs, Psychic- and Ghost-types with Crunch, and of course Liquidation in rain. Neko already talked about the importance of Barraskewda's extra speed, so I won't belabor that point. All in all, Floatzel's niche is its raw power, which just doesn't cut it against Barraskewda's coverage and Speed.
hii, mew can be used a few different ways, although i would say its not the best choice around these days
Here's the Fighting replays I could find:
Vikavolt with webs/bolt ball coverage and Alolan Golem for trapping stuff if you dont like Sandy Shocks (Socks better for Hazards)
I would think AlolaTales is viable, although giving up Klefki’s Spikes, Stealth Rock neutrality, and Prankster is dubious. The Stealth Rock weakness is also really bad, considering Fairy has no reliable hazard removal and you want your screens setter to come in multiple times. It could be seen, but I wouldn’t bet on it.
It's definitely "viable" on paper, but I struggle to think of a team comp where you'd actually want to use it. The issue with Atales on Fairy is that nothing on Fairy benefits from snow directly unless you're removing another weather, it has basically no defensive utility on Fairy beyond an Ice resist, and it's actually not a great Water answer because it doesn't resist the type and gets walled by Empoleon. As DBD said, it also faces stiff competition from Klefki who has far more apparent utility due to its key defensive niches and access to Spikes. Atales also actively hinders you in the Ice MU by buffing the opposing team (although it can serve as a Baxcalibur check). I think the main benefits Atales brings to Fairy is being a screens setter that can easily remove Quagsire to enable Azumarill sweeps and can also Encore setup sweepers, but it seems to have very limited utility outside of this and that alone to me isn't enough of a draw to use it. Overall, my initial impression of Atales on Fairy is that it feels like one of those D rank mons who is technically usable but is unlikely to see any major success in serious play.
Vikavolt and webs is interesting on Bug as a whole, and it’ll probably fit in over Lokix or Frosmoth (EDIT: definitely over Forretress), but I don’t see it defining Bug in any way.
Here's what I've been using for Bug post-DLC:
Is currently not too hot in Poison as meta prefers fast revenge killer (which sneasler does). BU Set still good, though that means you'll use both of them. On Fighting it can feasibly run an AV set to take a laughable amount of damage from Moonblast (though it'll lose to Hatterene if its under screens), and spread Knock and Poison because Toxic chain good. Also frees up Iron Hands to use the SD set if wanted
Bad on Poison as its outclassed by Gengar due to speedtier/coverage. Psychic you can use a scarf set with U-turn to possibly land a Poison into something like AV Hands, Sableye, or whichever wall that isnt Muk-Alola or Clodsire, or go Sub NP to annoy water and poison itself. It's strong enough to bust through unaware Quagsire btw.
Bad on Poison because of Galarian Weezing's existence, on Fairy it does remove Tspikes for you, but doesnt really do much. Beat Up set is weird since you do the same thing with Toxic, and you have Gunk Shot/Poison Tail for the magic bouncers.
Gliscor offers Flying a pretty great Electric-type immunity and access to utility like Spikes, Knock Off, and Toxic. Mandibuzz is a nice Defog user if you want to use Bulk Up Corviknight. Galarian Zapdos got Knock Off, so did Thundurus-T and Tornadus-T.
