Starters: Serperior gets an even stronger Leaf Storm or Giga Drain, Emboar gets one hell of a last-ditch Flare Blitz, and Samurott...doesn't get much.
Watchog: Two useless abilities. No change, still sucks.
Stoutland: Oh lordy. Not only a Sand Rusher, but now with Scrappy to click Return and not care, and Intimidate to aid its defensive capability.
Liepard: Because screw anything going before you. Prankster, then Limber to screw paralysis, and in case it should take a Knock Off, thanks! Unburden!
Elemental Monkeys: Starter ability plus Gluttony. Well, who knows if Gluttony will come in handy.
Musharna: Can move-scout as well as punish (some) status.
Unfeazant: Still got the short end of the stick for elemental birds. Rivalry+Super Luck Air Cutter
might be threatening if it didn't come off 65 SpA.
Zebstrika: Motor Drive is the big one (as if it needed to be faster already), while between Sap Sipper or Lightning Rod, you're sure to grab at least one beneficial power boost.
Gigalith: Five guys and a...Sand Forcer with Sturdy. Meh.
Swoobat: Simple+Unaware wins Calm Mind wars. Sadly, it doesn't even get Trick or Switcheroo to make something out of Klutz. Still an improvement.
Excadrill: Everybody was excited about this, and with good reason. Improved speed
and power for sand,
and it gets to keep Mold Breaker!
Audino: Go mega or go itemless. At least as a non-mega it keeps Regenerator.
Conkeldurr: Sheer Force+Iron Fist, hello. Oh, and then it can utilize Guts to boost even further. Geez, was base 140 not enough?
Seismitoad: Swimmer, Water Absorber, and hey, let's throw around poison for the heck of it.
Throh: Guts Mold Breaker with a flinch immunity. Mold Breaker distinguishes it from Hariyama, the other fat Guts mon.
Sawk: Mold Breaker with flinch immunity and...Sturdy. At least it can usually get off two hits.
Leavanny: But it's already powder-immune! At least it's not taking sand damage. Oh, and it's a Chloro sweeper that can fire off one hell of a Bug Buzz in a pinch.
Scolipede: Everyone's favorite Speed Booster, now with a couple of bonus abilities in Poison Point and Swarm.
Whimsicott: It Pranksters! Through Subs! And give it sun and it goes even faster! One of the best support mons in this format.
Liligant: Sun sweeper with confusion and status immunities (the latter only under sun). Click Petal Dance and win. (Well, you could, if Grass weren't such a crap attacking type.)
Basculin: Super hard Waterfalls that bypass the many Water immunities, and a forme-specific third ability. Unfortunately, it lacks the recoil moves (besides the common Double-Edge) to take advantage of either.
Krookodile: MoxieDate with Anger Point as a bonus ability.
Darmantian: Zen Mode is now mandatory. Prepare accordingly.
Maractus: Oh Lordy, switch in on a Water move and grab a +1
and healing. And then it has Chlorophyll.
Crustle: Weak Armor, but critproof and Sturdy. Still, just because it has 70/125 physical bulk doesn't mean it likes to compromise that (especially as a Shell Smasher).
Scrafty: MoxieDate with the ability to get rid of status.
Sigilyph: Tinted Lens doesn't help with immunities, and Wonder Skin is nice to dodge status. If you want to use something other than the Flame Orb set.
Cofagrigus: Mummy is
so much more powerful when it can take two or three abilities away and not just one.
Carracosta: Solid Rock
and Sturdy. Great pair for a Shell Smash Swift Swimmer. Also, Costa becomes possibly the best Weakness Policy user in the game, since barring Mold Breaker it pretty much
will survive an SE hit (that isn't Grass).
Archeops: If Archeops had another ability, everybody would be using it.
Garbodor: Stench is a nice improvement when it can flinch things, while Aftermath hurts what brings it down. And then it has Weak Armor, which can help it get fast enough to flinch things.
Zoroark: Illusion mindgames galore. (At least until Rotom uses Flamethrower.)
Cincinno: This will be its "Who's laughing now?" moment. Technician+Skill Link gives you a nearly 300 BP STAB and 187.5 BP coverage. The end, who cares about Cute Charm?
Gothitelle: Now it can do more than trap! Dangerous with a Competitive boost, and Frisk lets you scout for a Shed Shell or Mega Stone, so you can trap and Trick with confidence.
Reuniclus: Pivot without fear of hazards, and laugh at your newly-acquired Spore immunity. This one's gonna be tough to crack.
Swanna: No Defense or accuracy drops, no status in rain. Meh--which sucks, because I really like Swanna.
Vanilluxe: Healing in hail might help on top of Weak Armor. But of course, you need hail.
Sawsbuck: No Serene Grace movepool for you. But give it sun and it can go hella fast, while grabbing a +1 off Grass moves.
Emolga: Static+Motor Drive. Yay. It's Emolga.
Escavalier: Picks up a crit immunity, and of course Swarm has its uses.
Amoongus: An unwanted Effect Spore activation won't cease to annoy you. But it's a nice bonus with Regenerator.
Jellicent: Disabling a move and being Water-immune is a great combo, plus it blocks explosions.
Alomomola: Give it rain, and it can shrug off status in addition to resting up while benched and passing those huge Wishes.
Galvantula: Poor guy didn't pick up much. It can block Berry consumption, and there's Swarm, but it'll always be Compound Eyes Thunder.
Ferrothorn: No more worrying about a surprise HP Fire, which is pretty big, even if it's in-battle effect is minimal.
Klinklang: Got nothing, with its other abilities being Plus and Minus.
Eleektross: Go on with your no-weakness bad self. Just be careful, there's a
lot of Mold Breakers out there.
Beheeyem: Picks up Synchronize in case of status, which is something.
Chandelure: Infiltrator is just a nice ability in general, and now Chandy can have that and its Flash Fire boosts, with Flame Body as a bonus ability.
Haxorus: Can also block Berries, but Rivalry's hit-or-miss nature is a slight downgrade.
Beartic: Like Ice Body means anything for a Swimmer. It also has very fierce competition, even as a Grass check.
Cryogonal: Still the same.
Accelgor: Heals status in rain. Now, this whole Sticky Hold+Unburden thing...basically, use a Berry, so you're guaranteed to keep it until you need it, and then Unburden kicks in.
Stunfisk: Static is now a joke, and Sand Veil and Static aren't particularly valuable by themselves or in a combo.
Mienshao: Whiffed your Reckless High Jump Kick? Just head to the bench and rest up. Inner Focus provides a nice bonus as well.
Druddigon: Another Sheer Force Mold Breaker, with Rough Skin as a bonus (TankGon?).
Golurk: Shame the item slot's useless. Ah well, there's still Iron Fist No Guard Dynamic Punch!
Bisharp: Yes, it has other abilities. Enjoy a flinch immunity and Pressure to boot.
Bouffalant: With immunities to Grass and sound moves, it's a bit easier to get this in and start wreaking havoc with Reckless Head Charge.
Braviary: This thing has a couple of Sheer Force moves, it just can't fit them. Poor guy. Still a great Defiant user.
Mandibuzz: Sadly, Weak Armor drops count as self-inflicted (
source)
Heatmor: Gimme dat Flash Fire, and blocking stat drops is also nice.
Durant: Entrainment is pretty much necessary, or else you've just gone full Slaking. Never go full Slaking.
Hydreigon: Same old, same old.
Volcarona: Adds Swarm. Neither ability would be more than a bonus on anybody else anyway. It's still good.
Swords of Justice: Still Justified.
Forces of Nature, Therian Formes: Only have the one ability. Perhaps we should be grateful.
Tornadus-I: Defiant boosts are always nice, plus it can Prankster Bulk Up. (Cro set, though. Prankster Sleep Talk for the win.)
Thundurus-I: Usually goes special, but maybe Defiant will change your mind. Maybe. Still has Prankster as well.
Kyurem, Kyurem-B, Keldeo, Meloetta: Same as they ever were.