Abilities:
Since Gen III, Abilities have proved to be a major game mechanic, to the point of even making and breaking some Pokemon. Let's see what the new Abilities can provide for new and old Pokemon alike:
Ability: Sweet Veil
Effect: Prevents the user and its allies from the Sleep condition.
Known Users: Swirlix
Comment:
This possibly could be a Signature Ability due to it's name and implied way of achieving its effect: giving its allies a sugar high via osmosis. The only other Pokemon who I can see possibly getting this Ability is the Vanillite family, but even then their not described as being "sugary" like Swirlix, they're described as being living icicles who just so happen to also look like ice cream in a cup/on a cone. So the possibility of this being a Signature Move is very high, at least from what I can see.
So from first glance the Ability to keep your allies awake sounds like a great Ability since the only thing more broken than the Sleep condition is the "might as well be a OHKO" Frozen condition. However then you start to think "how often does Sleep come into play?". As of Gen V, there are 10 moves which can inflict the Sleep condition. By far the best one is Spore but its limited to 7 Pokemon. Speaking of which, 3 of these Moves are Signature Moves: Dark Void for Darkrai, Lovely Kiss for Jynx, and Relic Song for Meloetta. Dark Void and Lovely Kiss don't have 100% Accuracy but their reliable enough, however you'll rarely see either of them due to one being a Legendary thus in the Uber tier and there are other Ice- or Psychic-types better than Jynx. As for Relic Song, it only has a 10% inflicting Sleep as it's real use it to transform Meloetta into its Pirouette Form. Then we have the well known sleeping Moves: GrassWhistle, Hypnosis, Sleep Powder, and Sing. While a bit more common, these moves have non perfect Accuracy lower than the Signature ones thus are more likely to miss on top of their still low distribution. Finally we have Secret Power, which only has a 30% chance inflicting Sleep if you're in tall grass, and Yawn which only puts a Pokemon to sleep on the next turn, thus if the trainer switches out next turn their Pokemon won't fall asleep. So in all honesty, the only reason you'll ever ave to worry about the opponent putting you to sleep is if their strategy revolves around it which aren't a lot. However, while there are only 10 Moves that can inflict the Sleep condition, there is another Move which purposely puts your Pokemon to Sleep and is used more often then any other Sleeping Move: Rest. Rest puts your Pokemon to sleep in exchange for fully healing and curing the user. Many strategies involve using Rest, usually combined with an item that heals Sleep like a Chesto Berry, to provide a free full heal. However, because Sweet Veil will prevent the Pokemon from falling Asleep, Rest will fail making it more of a hindrance then advantage. So while the move can be helpful, many times you'll find that you don't need it and it could be preventing one of your Pokemon from healing via Rest. Use with caution.
This Ability pretty much assures Swirlix being a Support Pokemon, so I guess if you're using it you have the cons in mind and have worked around them. If Swirlix gets the right Moves or has the right allies, you can probably use Sweet Veil to run your own Sleep afflicting strategy without worrying about your opponent bouncing the status ailment back onto you with Magic Coat or Magic Bounce. Though to make it work Swirlix is going to need to have good defenses to assure it can keep Sweet Veil up.
As I said, the only other Pokemon I can possibly see getting this is the Vanillite family and I don't think they have the defenses to make any strategy with it work (besides, they like Ice Body for the healing in Hail (which they'll want up for 100% Accurate Blizzards)). Either I'm being unimaginative or Sweet Veil is indeed a Signature Ability.

I'MSOHYPERHYPERHYPERIDON'TTHINKI'LLBEABLETOSLEEP!!!!!
Ability: Fairy Aura
Effect: Increases the Power of Fairy-type Moves for all Pokemon on the field.
Signture Ability Of: Xerneas
Comment:
Our first Fairy Legendary is going to make sure you know the power of Fairy-types! Not only will it have a powerful Fairy-type Signature Move (which it gets STAB for) but it also has an Ability to increase the Power of all Fairy-type Moves! You might as well also make it so that any Dragon-, Fighting-, or Dark-types that don't have a type which resists Fairy-types faint instantly upon Xerneas being sent out! Anyway, this makes Xerneas the go to Fairy-type Legendary if you're running a Fairy-type team. Now most of the time it'll probably be only using this Ability to Power its own Fairy-type Moves up, but I've seen many Abilities which sometimes don't even factor in many battles so it could do worse. Now it does also power-up the opponent's Fairy-type Moves as well, but if you're going to use Xerneas you probably already know this thus aren't going to partner it up with a Dragon-, Fighting-, or Dark-type. Actually, with this Ability you'll probably want to partner Xerneas with a Pokemon resistant to Fairy-types so that your opponent would be less likely to use one (bonus points if that Pokemon is also part Fairy-type or can learn a Fairy-type Move, like Mawile).

Dragonite is probably feeling a little bit sick right now...
Ability: Dark Aura
Effect: Increases the Power of Dark-type Moves for all Pokemon on the field.
Signture Ability Of: Yveltal
Comment:
Now while Pokemon often seen used in battle who are Dark-type probably aren't used because of just its Dark-type, Dark-type Moves on the other hand are used because they are Dark-type thus hit both Psychic- and Ghost-types super effectively. However Dark-type moves aren't very powerful, probably because their based on "dirty tricks" which are used to get a slight upperhand against your opponent but not the main method you'll be winning by. However Yveltal plans on changing that using its Ability to power-up Dark-type moves making them a bit more potent. So we have our normal Dark-type damaging moves like Crunch, Dark Pulse, Night Slash, Night Daze, and sometimes Foul Play, but Dark-type Moves are far more than that. Knock Off makes the opponent lose its hold item which can ruin their strategy, Pursuit hits an opponent who's about to switch out as a final reminder, Sucker Punch works and goes first if the opponent is attacking that turn which teaches them why attacking others isn't such a nice thing, Payback & Assurance are the opposite by doing double the damage if attacked first showing what goes around comes around, Foul Play uses your opponent's own Attack stat punishing them for being so strong, and finally Punishment does more damage the more the opponent setup making them regret it. All in all, Dark-type moves may be a bit gimmicky but if you can get them to work they can really annoy and put a number on your opponent but probably not knock them out. However with Dark Aura, maybe it's time for these Moves to start dishing out real damage. And what better way to show this than with Yveltal's own Dark-type Signature Move which is probably already powerful but Dark Aura just makes it the more devastating! Dark Aura of course also works for Yveltal's allies so while you may not want all of them being Dark-types you might want to make sure they at least know a Dark-type Move. However if you do go with an all Dark-type team, you'll at least not have to worry about your opponent turning Dark Aura against you by powering up their Dark-type attacks since Dark resists itself. Though you may not want any Psychic- or Ghost-type Pokemon (at least ones who aren't also a type resistant to Dark) on your side.

Odd it's also called "Dark Aura" in Japan when the Dark-type is called "Evil"-type there.
Ability: Cheek Pouch
Effect: When the user eats a Berry it'll heal some HP in addition to the Berry's effect.
Unown Users: Dedenne, Bunnelby
Comment:
Being both Dedenne and Bunnelby are learning it it's safe to say it's not a Signature Ability. However it does seem like it'll be limited to Pokemon based on the Glires clade/granorder, basically Pokemon based on rodents (mouse, rat, squirrels, chipmunks, etc.) and lagomorphs (rabbits, hares, & pikas (no, this isn't the basis for Pikachu)) which are well known to stuff food in their cheeks.
Having an Ability which heals you is always handy to have as you can work that into a strategy, and if that strategy also includes a Berry then together you make a dangerous combo. Berries provide a wide range of effects when eaten, some proving better than others over time, and can be used to give some Pokemon either a second wind or keep them battling a little bit longer. Some of the most used are the Sitrus Berry which heals 25% of the holder's HP (is eaten when holder's HP goes below half its max HP), Lum Berry which cures any status (activates upon infliction), Chesto Berry which awakens the user upon falling Asleep (is often combo with Rest. Chesto assures that it'll most likely only be used when the holder Rests unlike Lum which could activate before if the opponent inflicts another status ailment on the holder), and the Yache Berry is sometimes used by Dragon-types who are quadruple weak to Ice-types by cutting the move's power in half (used upon getting hit with Ice-type move. There's actually a group of Berries which does this for all the types). There are other Berries, but their effects are either not worth it, overshadowed, or too risky since they activate when the user has low HP. However, what if the user heals a bit after eating the berry? This is where Cheek Pouch gets interesting as it could make some combos viable to those Pokemon with Cheek Pouch. Now sure you can use it to get more HP with a Sitrus Berry or healing plus curing with a Lum Berry, but then we have the "pinch" Berries. The "pinch" Berries increase one of the holder's stats when its HP falls below 25%. There's one for each stat except HP, obviously. Now obviously the most useful of these are the offensive and Speed ones, though all of them generally on not use since you need to have your Pokemon close to fainting. However if you combo them with Cheek Pouch, you'll probably get up to a certain amount of HP which makes using these Berries worth it. Of course this Ability might not be useful for the "type halving" Berries since most of those are intended to activate when the user is at full HP. But as I said mostly Dragon-types quadruple weak to Ice-type have one of those, the Yache Berry, and I doubt they'll be getting this Ability. It'll also be useless for the Rest/Chesto combo since Rest heals the user completely. Speaking of healing, a lot of this speculation also has to do with how much HP does Cheek Pouch heal? If it's something like 10% of 12.5%, then ignore everything I said above about the "pinch" Berries as that's not a lot and it'll just turn into a nice additional healing for Sitrus Berry and Lum Berry.
Speaking of which, going to the known users, honestly they'll probably just combo it with a Sitrus Berry and maybe a Lum Berry anyway. I guess they could try a "pinch" Berry strategy out if they have good enough stats, but only if Cheek Pouch healing is something like 25% of max HP. If they have high Speed you can go for the Liechi Berry (Attack) or Apicot Berry (Special Attack), but if their Speed is decent and REALLY want to test out the "pinch" Berry strategy you can use a Salac Berry (Speed). However if their Speed is low (or Cheeck Pouch healing isn't that much) then just use Sitrus or Lum if you decide you want to use Cheek Pouch.
As I said above, rodent and lagomorph Pokemon probably will be getting this Ability. With that said, I can see this being used in an interesting combo with Emolga. Emolga consumes a Liechi Berry, increases its Attack by 1 stage, gets some HP back from Cheek Pouch, and uses Acrobatics which now doubles in Power because Emolga is no longer holding an Item! It's sort of like the Flying Gem combo, except the increase Power is permanent and if things start getting sticky it can sacrifice the increase by using Volt Switch of U-turn to retreat. Though this does mean Emolga can't use its Motor Drive Ability for safe switch-ins and increase in Speed. Other rodent/lagomorph Pokemon are pretty much the rest of the Pikaclones and generational rodent. Going through the Pikaclones: Raichu could go with either a Liechi or Apicot Berry (Pikachu much prefers holding onto its Light Orb), Pichu could probably return to full HP using this with an Oran Berry in Little Cup, Plusle & Minun could either use a boost from a Apicot or Salac Berry, and Pachirisu probably would go with a Salac for more speed (if it wants to give up Volt Absorb). As for the generational rodents (Ratata family, Sentret family, Zigzagoon family, Bidoof family, & Patrat family) they'd probably take Liechi or Salac but probably would rather have Sitrus or Lum. Finally we have the rabbit Pokemon, the Buneary family, which probably would prefer a Sitrus or Lum but I guess can make use of Liechi.


Actually it looks like they already are storing something in their cheeks.
Ability: Parental Bond (Japanese: Parent and Child Love)
Effect: The user attacks twice each turn.
Known Users: Mega Kangaskhan
Comment:
Being Kangaskhan is the only Pokemon which is a parent/child combo, I'm going to say it's highly likely that this is a Signature Ability for Mega Kangaskhan. Because of this I'm going skip over what Pokemon could get this Ability, but I will say that I can't think of any Pokemon which wouldn't like to attack twice per turn... of course, that's assuming how the attacking twice works.
Because Mega Kangaskhan was revealed at a tournament in a trailer and only some basic info was given, we don't know how Parental Bond exactly works. Yes, it could work just as the description says and Mega Kangaskhan uses the same Move that was selected twice, but that sounds like it would be a tad bit overpowered or even broken. Normal Kangaskhan has a high Attack, good Speed, and can learn a variety of attacks (as traditon with Normal-types). With Physical attacks it can learn from Gen V it can learn 13 Types: Normal (Return, Facade, Double-Edge), Dark (Crunch, Sucker Punch), Dragon (Outrage), Ground (Earthquake), Fighting (Drain Punch, Hammer Arm), Flying (Aerial Ace), Ghost (Shadow Claw), Rock (Rock Slide), Water (Aqual Tail), Fire (Fire Punch), Ice (Ice Punch), Steel (Iron Tail), and Electric (ThunderPunch). That's quite the coverage it has and it attacking twice not only means the Power is practically doubled but the first hit could be used to break a Substitute, the Ability Sturdy, and a Focus Sash which allows the second hit to deal damage and possibly faint the opponent. Because of all this the question of there being a catch has been asked and thought on. If there is a catch, a few possibilities have been suggested: (1.) The Move's Power is split between the two hit (so if you use Crunch which has 80 Power, both hits would be 40 Power), (2.) The second hit is half the Power (using Crunch again, the first hit would be 80 Power and the second hit would be 40 Power). The former is more balanced and still gives you the Substitute/Sturdy/Focus Sash breaking but doesn't make sense as why would the Power be cut in half? The latter still is a bit overpowered but it does make some sense if you think that the first hit is done by the mother and the second hit is done by the child (hence the half damage. Also remember its the child Kangaskhan which Mega Evolves, not the mother, so the mother's strength is normal while the child has become strong enough to now participate in the battle). Also I'm going to assume this only works for Moves which Attack, because using two Status Moves in row is either broken or pointless. It can be broken if you're using stat boosting/decreasing Moves and Kangaskhan can learn Leer (decrease opponent's Defense by 1 stage), Tail Whip (decreases opponent's Defense by 1 stage, adjacent opponents in Double and Triple Battles) Double Team (increase user's Evasion by 1 stage), Work Up (increase user's Attack and Special Attack by 1 stage each), Helping Hand (increases the Power of a allies attack by 50% next turn. Can stack), and Spite (decreases the PP of the opponent's last Move by 4). While Leer and Tail Whip might not be used as the opponent can switch, Kangaskan could use Double Team to quickly become untouchable, Work Up to have its Attack quickly become Sweeping levels, Helping Hand (if in a double battle) to double the Power of an allies attack, and Spite to remove all PP from a move in one or two turns. However this can be pointless for Status Moves which only would work on the first use like Endure, weather summoning Moves, Protect, Safeguard, Rest, Attract, Swagger, Substitute, Disable, Focus Energy, and Foresight. Inbetween the two of these is Toxic and Roar and I guess you could use it to assure Toxic works (though it has 90% Accuracy to being with) while Roar could be used to make the opponent keep switching Pokemon which will activate Entry Hazards. So in the end, however it'll work, I think it'll only work for attacking Moves.

Another variation of the "child's hit is weak" is the the child attacks first with half Power and then the mother attacks second with full Power, though that does risk possibly not breaking a Substitute.
(Continued next post)