Over Pokemon's long history, almost 1000 different moves have been added to the games. Some are powerful, some are weak, some are special, some are physical, some only have status effects. Some moves, crucially, are quite rare, only being learned by a handful of Pokemon or even just one and its evolutions. These are called signature moves. Some of them are singlehandedly responsible for bringing Pokemon into the limelight, while others make trainers thankful that the move doesn't bloat the movepools of other Pokemon.
Many iconic critters get their own signature move, primarily Legendary Pokemon or starters. A few have even been distributed to others, losing their signature status. These moves, however, have retained their signature status, and for good reason.
10 Hydro Steam
Harsh sunlight has always been a hurdle for Water-types, acting as a way for Fire-types to gain equal footing against a type they would normally be disadvantaged against. However, with the introduction of Walking Wake, there's a Water-type Pokemon who not only functions in Sun, but flourishes.
Walking Wake's signature move, Hydro Steam, is unique in that it cannot be weakened by Harsh Sunlight as other Water-type moves are. It actually becomes stronger in harsh sunlight. This move, combined with Walking Wake's Protosynthesis, allows it to easily defeat Fire-types that would attempt to take advantage of the sun.
9 Triple Arrows
Most moves have some kind of secondary effect, be it a small chance to burn or a chance to change the user's stats. Triple Arrows, however, has not just one, but three secondary effects.
First, it has a high critical hit rate, giving it a chance to bypass the opponent's defenses and hit harder. Secondly, it has a 50% chance to lower the target's Defense stat. Lastly, Triple Arrows has a 30% chance to cause its target to flinch, preventing the target from acting.This combination of effects makes Triple Arrows a widely versatile move that Hisuian Decidueye can make great use of.
8 Salt Cure
Garganacl stands out as one of Pokemon Scarlet and Violet's premier defensive Pokemon. Despite being a Rock-type, a type infamous for its lackluster defensive utility, Garganacl has every tool it needs to be a great defensive Pokemon: The ability to heal, fantastic defensive stats, and a great Ability.
One of Garganacl's best tools is its signature move, Salt Cure. This move applies a damage-over-time effect, allowing Garganacl to passively damage Pokemon while it weathers damage from opponents. Furthermore, Salt Cure deals increased damage-over-time to Steel- and Water-type Pokemon, which typically make great use of their types' defensive qualities. On top of this, Salt Cure is technically an attack, dealing a bit of damage on top of applying its damage-over-time effect.
7 Ceaseless Edge
Entry hazards were introduced in Pokemon Gold and Silver, and have been immensely influential since their debut. The ability to deal chip damage when a Pokemon switches in can put a Pokemon into just the right HP range to knock it out with a well-placed attack. Of course, most entry hazards are status moves, letting them be blocked by Taunt.
It goes without saying that an attack that applies entry hazards is quite revolutionary. Hisuian Samurott's Ceaseless Edge is one of those moves, being a devastating Dark-type attack that deploys a layer of Spikes after use. On top of this, it also has a high critical hit rate, which is always useful for damage purposes.
6 Stone Axe
Spikes is one thing, but Stealth Rock is arguably the most potent entry hazard of all; dealing massive damage based on a Pokemon's weaknesses to the Rock-type. Pokemon that are crucially weak to Rock-type attacks are devastated by Stealth Rock, taking 50% of their max health on switch-in without proper protection.
As such, Kleavor's Stone Axe outranks Ceaseless Edge for its ability to set up Stealth Rock through Taunt. On top of this, the Rock-type has good offensive capabilities, and can hit many Pokemon for super effective damage.
5 Clangorous Soul
Prior to Pokemon Ultra Sun and Ultra Moon's release, Kommo-o wasn't particularly good for a Pseudo-Legendary, but it wasn't particularly bad either. It has balanced stats across the board. As a result, Kommo-o faded into obscurity until the updated rereleases of Gen 7 granted it a signature Z-Move, Clangorous Soulblaze.
Clangorous Soulblaze not only hit with the force of a truck, but also gave Kommo-o a +1 boost to all of its stats. This singlehandedly put Kommo-o on the radar, and even the removal of Z-Moves wasn't going to stop Kommo-o. It was granted the signature move Clangorous Soul, which boosted all of Kommo-o's stats in exchange for a bit of HP on use.
4 Geomancy
Being Pokemon's first Fairy-type Legendary would be worthy of celebration in and of itself, but Xerneas's true claim to fame is its signature move, Geomancy. Geomancy has the user charge up, then receive two Quiver Dance boosts on the next turn. Having three of your stats sharply boosted is already ridiculous, so it's balanced by the requirement of taking a turn to charge this formidable Fairy move.
In practice, though, Xerneas can just equip a Power Herb to nullify that drawback and gain an instant power boost, at the cost of taking up the item slot. Even then, it's hard to call that a drawback when clicking it puts Xerneas in an easy position to knock out anything in its path with a Geomancy-boosted Moonblast.
3 V-Create
It's said that Victini brings victory to anyone who fights alongside it. With the might of V-Create behind it, this is understandable. This move has one of the highest base powers of any attack in the game that doesn't knock the user out when used, clocking in at a whopping 180.
That said, V-Create isn't perfect: when used, it lowers the user's Defense, Special Defense, and Speed stats. Though you can use it in succession without losing damage, you'll put yourself in a position to be knocked out by any surviving foe or its switched-in replacement. It's to be used with care, but very strong indeed, even if Victini's Attack stat isn't the highest around.
2 Rage Fist
Prior to Pokemon Scarlet and Violet, the most powerful non-Z-Move attack was Explosion. Boasting 250 base power, Explosion put the hurt on anything in its path in exchange for knocking out the user. Annihilape, however, laughs in the face of Explosion. Though Annihilape's Rage Fist starts off at a measly 50 base power, Rage Fist grows in power every time Annihilape is hit by an attack - which, if you're at all familiar with battling, will happen quite a lot.
Even two hits puts Rage Fist at a base power of 150, becoming the strongest Ghost-type attack by a wide margin. It doesn't stop there, either: Rage Fist does have a limit, but its limit is a monstrous 350 base power, beating Explosion by 100 points. Rage Fist doesn't even have any drawbacks either, with the arguable exception of being unable to hit Normal-type Pokemon (Explosion, by contrast, can't hit Ghost-types).
1 Last Respects
Last Respects functions similarly to Rage Fist, being a 50 base power Ghost-type attack that scales in power based on a condition. This move's condition is how many of your Pokemon have been knocked out. Sending out Houndstone, Last Respect's user, after all of your Pokemon have been knocked out will put Last Respects at 300 base power, more than enough to put other attacks to shame.
It's impractical in a lot of scenarios and won't often hit for its full potential, but this remains one of the most unique moves the series has ever seen.