A Pokemon has many qualities that make it unique. A Pokemon's nature gives it a sense of individuality, and its Effort Values help it stand out statistically from others of its kind. A Pokemon's Ability, however, is perhaps one of the most essential qualities a Pokemon can have. Introduced in Pokemon Ruby and Sapphire, abilities have played a significant part in Pokemon since their inception, providing powerful passive effects ranging from immunity to specific attacks to being key factors that the Pokemon's playstyle entirely revolves around. And, as Pokemon becomes more and more populated, so too does the pool of abilities for Pokemon to draw from. And some of them are unique to specific Pokemon, earning the title of signature ability.
Signature abilities can range from reskinned copies of existing abilities to gimmicks that the Pokemon centers around. Some of these abilities are fantastic, and some of them are not - some of them are so strong that it's no wonder why the ability isn't more widely distributed. However, that begs the question - of the signature abilities, which ones are the best? Let's take a look.
10 Purifying Salt
Garganacl's Purifying Salt is one of the premier reasons Garganacl is perhaps one of the best defensive Pokemon we've received in recent years. Purifying Salt has two great effects; firstly, Purifying Salt provides immunity to status ailments. An immunity to status ailments is incredible for a defensive Pokemon, preventing things like Toxic from wearing Garganacl down. And though this also prevents Garganacl from using Rest, Garganacl can heal itself with Recover without putting itself to sleep.
Secondly, Purifying Salt also halves the damage taken from Ghost-type attacks. This may not seem like much, but the Ghost-type has stood out as a fantastic offensive type. Ghost hits only two types for super effective damage, and is only resisted by Dark-types. However, this also means that Ghost-type attacks hit every other type for neutral damage, which is fantastic. However, Purifying Salt stops those pesky Ghost-types on multiple fronts - both in the damage and status department.
9 Unseen Fist
In any competition, it's important to maintain fairness so that both sides have an equal opportunity to achieve victory. For example, moves like Protect allow you to block any move, giving you time to have a move like Leech Seed drain the last bits of health of a Pokemon currently sweeping your team. Protect, and its many variants, let trainers turn the tides of battle, should they be so lucky, giving everyone a fair and equal chance at victory. So, it's not hard to see why Urshifu's Unseen Fist is just completely ridiculous.
Unseen Fist allows Urshifu's contact moves to bypass Protect and hit Pokemon anyway. And you may think, "oh, contact moves, at least there's a caveat, right?" Well, only seven of Urshifu's potential moves don't make contact - the rest do. You'd have to be crazy not to run at least two contact moves on Urshifu, so that caveat of only contact moves triggering Unseen Fist may as well not exist.
8 Soul-Heart
Moxie, Beast Boost, Chilling Neigh, Grim Neigh... These abilities boost one of the user's stats after KOing a Pokemon. And this can't be understated - that's a great effect! Many users of Moxie stand out as powerful sweepers for their ability to snowball out of control and devastate the opponent's team. However, Soul-Heart, the signature ability of Magearna, stands out among these abilities. Unlike the others, Soul-Heart doesn't necessitate the user to KO a Pokemon - whenever any Pokemon faints, Soul-Heart boosts the user's Special Attack.
It's easy to see why this ability could be slightly overpowered, especially on a Pokemon like Magearna with a devastating Special Attack stat of 130. On top of moves like Shift Gear and Stored Power, which lets Magearna hit ridiculously hard with the right amount of stat boosts, Magearna takes great advantage of Soul-Heart to rip opposing Pokemon to shreds.
7 Fur Coat
A tried-and-true method to making something strong is to take one of its numbers and to double it. What could go wrong? And as such, Fur Coat stands out among Pokemon's many abilities for making Furfrou, an otherwise generic Pokemon, into a defensive powerhouse. Fur Coat doubles Furfrou's Defense stat, letting it take physical hits like a champ.
And, when considering Furfrou's Normal-typing, Fur Coat's usefulness increases. After all, Normal only has one weakness to the Fighting-type - and only four of the available Fighting-type attacks are Special. As such, Furfrou is uniquely suited to take effectively neutral damage from its one weakness, a property only shared by rare situations like Eelektross's Levitate and pre-Fairy-type Spiritomb.
6 Huge Power
Much like Fur Coat, Huge Power (and, by extension, its copy Pure Power) is one of those abilities you can't go wrong with. Everyone is a fan of big numbers, and Huge Power makes a very important number big - the user's Attack stat.
Of course, doubling the user's Attack stat could be very dangerous in the wrong hands, so Huge Power is distributed with immense precision. Huge Power's most famous user is Azumarill, who has a devastating attack stat of 50. Despite this, Huge Power can also be given to other Pokemon through moves like Skill Swap - and hey, a Pokemon like Slaking would much rather have Huge Power, wouldn't you think?
5 Delta Stream
There are many mysteries surrounding the Pokemon franchise. What is under the truck near the S.S. Anne? What's up with the ghost girl in Lumiose City? And why, oh why, did Rayquaza, of all Pokemon, get a Mega Evolution? Regardless of whatever design decision brought it about, Mega Rayquaza stands out as one of the most powerful Pokemon of all time. As such, it has a suitably powerful ability.
Delta Stream is the upgraded version of Rayquaza's Air Lock; rather than completely nullifying weather, Rayquaza now summons its own weather condition, Strong Winds. Strong Winds not only overrides other weather conditions, but also removes the weaknesses of Flying-type Pokemon. What was previously Rayquaza's devastating 4x weakness to Ice is now a regular 2x weakness, and Rayquaza now resists Electric-type attacks rather than taking neutral damage. Strong Winds lets Rayquaza take more hits than it could, and Rayquaza already received a sizable defense boost from its Mega Evolution.
4 Desolate Land
For years, the weather wars between Groudon and Kyogre raged in Kyogre's favor. Its signature weather further boosted Kyogre's STAB Water-type attacks, whereas Groudon gained a second STAB thanks to harsh sunlight - a useful tool, but not one that would help it overtake its rival. For a while, it seemed like Groudon was doomed to be the butt of every joke - that is, until Groudon obtained its Primal Reversion in Omega Ruby and Alpha Sapphire.
At long last, Groudon had an edge over Kyogre; the extreme weather condition summoned by Desolate Land not only boosted Primal Groudon's newly acquired Fire-typing, but also provided a complete immunity to Water-type moves. While Kyogre could turn the tables with its own Primal Reversion, Primal Groudon's Desolate Land forces Kyogre onto a playing field stacked in Groudon's favor - and it was a long time coming.
3 Imposter
Everyone's favorite copycat, Ditto, doesn't have much going for it. Ditto's entire gimmick is that it transforms into a copy of its opponent - moves and all. Its only learnable move is Transform, but sometimes that doesn't cut it. If you want to get ahead of the curve, try giving your Ditto its hidden ability, Imposter; this makes it so Ditto will automatically transform into its opponent when switching in.
No worrying about being knocked out is required! Imposter can be quite the hurdle to jump over for your opponent, as you can use Imposter to turn a potential sweep against your foe, or use it to scout out your opponent's moves. It's a pretty versatile ability for such a one-trick pony like Ditto.
2 Good as Gold
For Pokemon #1000, it's no wonder GAMEFREAK pulled out all the stops to make Gholdengo as good as it is. Good as Gold grants Gholdengo an immunity to status moves, and this ability is just one of the reasons Gholdengo is such a force to be reckoned with. Picture this: you're trying to beat Gholdengo. You think, "oh, maybe I can try and lower its defenses with Screech or Fake Tears?" Nope, those are status moves. Or, perhaps, you're trying to remove entry hazards - Rapid Spin won't work, as Gholdengo is a Ghost-type, so you try Defog. Defog, too, is a status move, so that doesn't work either. All you can do against Gholdengo is attack - and thanks to its Steel-typing, Gholdengo has many resistances to take advantage of.
1 Wonder Guard
Shedinja is infamous for being the epitome of a gimmick-centered Pokemon. It has 1 HP, a hardcoded limit that cannot be circumvented, yet it also has tangible Defense stats. Its other stats aren't that great either, with its highest stat being a mediocre 90 base Attack. And yet, for all of its faults, Shedinja remains in the fight thanks to its ability, Wonder Guard.
Wonder Guard would be completely ridiculous if it were on any other Pokemon, and perhaps that's the point; Shedinja can only be hit by super effective attacks. Of course, Wonder Guard doesn't block indirect damage like Sandstorm or Stealth Rocks, but let's ignore that for now.