With Magneton being gone, the meta is probably going to revolve around Sneasel + Gallade for a while now. The core is so incredibly potent with Sneasel trapping Psychic and Ghost types or softening up walls with its powerful Knock Offs for Gallade to clean up. I can see Mawile shooting up in usage again because it either beats or pivots into over half of the S / A+ threats and Baton Pass allows it to keep momentum on your side easily as well. Tauros and Fletchling beat it 1 on 1 but getting an Intimidate off can go a long way in preventing them from running over you. It's not the most creative core in the world and I'm sure people have used it before, but Mawile + Lanturn + Hariyama sounds like a really nice core. Struggles with hazards and lack of speed, but you have 3 more slots to cover that and you're already pretty sound defensively.
Getting back to Gallade, its lack of counters means it probably needs to get banned sooner than later. SD / CC / Psycho Cut / Knock Off ragaves everything slower than it outside of Mawile, Granbull, and Colbur Psychics and the latter can't even really do anything back. I suppose they can all pivot out to a revenge killer via U-Turn (Xatu, Uxie, Mesprit) or Baton Pass (Musharna), but that only works once. Unless the revenge killer is CB Sneasel that clicks Pursuit (yay coin flips), nothing can prevent Gallade from setting up again and doing massive damage then. So yeah if we ignore Granbull for a while, the best way to deal with Gallade is either revenge killing or not letting it set up via offensive pressure. Granted, it isn't the easiest thing in the world to set up in the first place, but between its good special bulk and decent offensive pressure at +0, it's reasonable to assume Gallade will find a way to set up against most teams. I didn't even talk about the variety of Gallade's sets, because I don't know them as well and SD is the one that's really ban worthy, but they undoubtedly add to Gallade's brokenness.
This might be more controversial, but maybe we should look at Sneasel as a potential suspect in the future as well. It's easily one of the most defining forces in this metagame. It pressures 90% of the tier with its Speed and power and it's a nightmare to face for offensive teams. If it's CB, it's a great team player by trapping the Ghost / Psychic types your opponent needs to check other members of your team (hi Gallade!). On the other hand, it's got plenty of checks and counters, it's SR weak and it's very frail with a CB attached. Saying that removing Sneasel will make the metagame better, is a dangerous argument because Sneasel keeps a lot of the Psychic types in check that might rule the tier otherwise. But yeah Sneasel is very, very good, so it probably deserves some kind of discussion.
I didn't face a single SmashPass team while laddering for reqs, but by looking at some replays and reading the arguments in this thread, it should definitely be nerfed in some way.
This thread could serve as good inspiration and if you haven't read it already you should :o But yeah, I feel like it might be easiest to just quickban Shell Smash + Baton Pass for now and wait and see what OU does. If they go through with "can't pass boosts in 2 different stats or +4 boosts all around", that can be extended to NU later, but it doesn't seem like OU will reach a verdict very soon. The priority should be getting rid of SmashPass right here and now in NU though.
edit: ugh I'm becoming as big a thyhard as finch