I'm new to UU (Yes I know, another guy said it above me, but my question is different). So what are the "Top Tier Threats" that I need to look out for?
(Oh, and is Bulk Up Scrafty viable? I've always wanted to use Scrafty :D)
Like Petrico94 pointed out, the Viability Rankings Thread is something you should look at because it gives you a gist of what works and what doesn't in the tier. The
UU Threatlist, even though it's still in the works, is also something you should look at because it gives you a basic overview on
why a threat is good.
Also this though it isn't finished. Some things to keep in mind are that most of the offensive Pokemon in the tier are Dark-types, Fighting-types, and Fire-types, so they are in general very threatening. I'll go over a couple really quickly, and that UU home home to powerful attackers from both ends of the spectrum. I'll go over a couple of Pokemon to give you some examples.
Hydreigon: Hydreigon normally runs one of two sets, Scarf or Roost + LO, though the former is more common. It has a two great STABs that it can rely on and has great attacking stats to support it. It's Dragon-typing also gives it a couple of nice resists to Water- and Fire-type attacks' this, in tandem with with it's natural bulk, lets it switch into most Pokemon in tier rather easily. As you can probably guess, Fairies and Fairy-type moves in general are troublesome fore it, as with Fighting-type moves from the likes of Infernape, Mienshao, and Hercross.
Heracross: Heracross is easily one of the most versitile Pokemon in the tier, having two great abilities and a multitude of sets. Heracross can function as an efficient wall breaker when using the Guts + Flame Orb set, Swords Dance, or even opting for the Choice Band set. It has two powerful 120 Base Power moves in Mega Horn and Close Combat that also get boosted by STAB. As you can tell, Flying-types put a full stop on it, and it's subpar Speed is also disappointing for an offensive Pokemon like itself.
Houndoom (Mega): Mega Houndoom is particularly Scary because it has the ability to force switches, and in turn, the ability to set-up. There is the standard Nasty Plot set that carries Fire Blast and Dark Pulse for STAB and Flame Charge to Boost Houndoom's Speed, though Substitute can be used over it. The other, less common set is the Sunny Day one. It can set-up Sunny Day, and then process to wreak havoc with it's insane Special Attack backed by the Sun and Solar Power.
Mienshao: Mienshao is one of the best Revenge Killers in the tier, and like Heracross, has a couple of viable abilities it can use. Reckless can be run to boost Hi Jump Kick's power even further, while Regenerator can be used to bring Mienshao back to healthy levels for late-game cleaning. Any set other than Scarf is uncommon, so you shouldn't worry about it too much.
Honchkrow: Honchkrow one of the most powerful Physical Attackers in the tier that can passively set-up with Moxie. It has access to the coveted Sucker Punch it can use to put a quick end to frail, choice-locked Sweepers. It also has access to Pursuit, which, along with Sucker Punch, can play mind games with the opponent. Flying STAB is one of the best in the game, so Honchkrow's Brave Bird is something to be wary of.
Nidoking: Nidoking is the premier Special Wallbreaker in the tier. It has access to an incredibly diverse movepool, including Fire Blast, Thunderbolt, Earth Power, Ice Beam, and Earth Power among others. It's also the best answer to Florges and has a wonderful ability in Sheer Force, which boosts all of Nidoking's attacks at the small cost of losing out on secondary affects. This also applies to Life Orb damage! The same also applies to Nidoqueen, who also has similar stats and can afford to run a Modest nature.
I'm not going over the drops because they might be banned, but I hope I helped!
noh8pls