Pokémon Scarlet & Violet have brought a new generation of fantastic Pokémon, including several new abilities and signature moves along with the Terastal mechanic that completely redefines the game and its mechanics.
Terastallizing allows a Pokémon to transform into a single type while keeping the Same Type Attack Bonus from their previous types. This means that Dual-type Pokémon can have up to 3 different STAB moves. Fortunately, there are multiple Dual-type Pokémon that are incredibly powerful in the game's ninth generation.
10 Cyclizar
Cyclizar is a Dragon/Normal-type with great Speed. It doesn't hit very hard, but it has a move pool that includes some of the best utility moves in the game, like Rapid Spin, Knock Off, and U-Turn.
Cyclizar's signature move, Shed Tail, is undoubtedly one of the strongest moves in the game and one of the biggest changes to competitive battling in Scarlet & Violet. The addition of Cyclizar changes the game all by itself. Not only that, Cyclizar's ability Regenerator combos perfectly with Shed Tail and allows it to stay healthy even with the HP cost of its signature move.
9 Chien-Pao
Chien-Pao is a Dark/Ice legendary Pokémon with very high Attack and Speed. Like the rest of its counterparts in the same legendary series, Chien-Pao has an ability that lowers one stat of all other Pokémon except itself.
In the case of Chien-Pao, its "Ruin" ability is "Sword of Ruin," which lowers all other Defense stats on the battlefield. This works well with Chien-Pao's high Attack and Speed, turning it into a true glass cannon. However, the downside of being a glass canon is that if Chien-Pao is faced with an opposing priority move or faster Pokémon, it may be immediately KO'd without the ability to do much.
8 Iron Valiant
Exclusive to Pokémon Violet, Iron Valiant is a Fairy/Fighting mixed damage Attacker. It has the ability Quark Drive, which will increase its strongest stat, which will either be Attack, Special Attack, or Speed, depending on nature and EVs.
While they do have some layover, Fairy and Fighting are very complimentary offensive types that can hit any type except for Poison with neutral damage and cover many super-effective bases. Thankfully for Iron Valiant, it has access to Zen Headbutt in order to deal with pesky Poison Pokémon that would have otherwise walled it. This, along with its ability to hit hard with both Physical and Special moves, means that there are no Pokémon that truly wall Iron Valiant.
7 Chi-Yu
Chi-Yu is a Fire/Dark legendary with a unique ability in Beads of Ruin, which allows it to lower all other Pokémon's Special Defense stats. It's similar to the rest of the "Ruin" abilities from the same line of legendaries, but it may be the best ability of the four.
Aside from just being one of the weirdest looking Pokémon of its type, Chi-Yu is also arguably the strongest of its legendary group, partially due to the fantastic synergy between its ability and stats. Chi-Yu doesn't just weaken the Special Defense of its target, it attacks with a remarkable 135 Special Attack to ensure that its weakened foe either has to switch out or take a ridiculous amount of damage.
6 Kingambit
Kingambit is the Steel/Dark evolution of Bisharp. In exchange for some speed, Kingambit becomes much stronger and bulkier. Its ability, Supreme Overlord, gives it additional Attack, depending on the number of defeated allies.
While most of the best dual-types in the generation are either legendaries or "Paradox Pokémon," Kingambit is one of the strongest Pokémon available in the wild since it can be evolved from the easily catchable Bisharp. After a boost from Supreme Overlord, Kingambit can destroy teams with Sucker Punch. Even if it isn't using priority moves, Kingambit can survive a few hits despite its low Speed thanks to fantastic bulk.
5 Great Tusk
Great Tusk is the Scarlet-exclusive version of Donphan. It's already made some noise in the competitive scene due to its very effective Ground/Fighting typing and fantastic physical bulk and Attack.
While fans may initially think that Great Tusk's typing makes it especially weak in trying to deal with Flying-types. However, Great Tusk has access to both Rock Slide and Stone Edge, making it easily capable of dealing with the only typing that its STAB moves struggle with. It covers all the bases, and the main weakness Great Tusk users will need to watch out for is its very low Special Defense.
4 Roaring Moon
Roaring Moon is the past version of Salamence, a Pokémon that was already one of the best Dragon-types in the game. The Dragon/Dark Roaring Moon rivals its predecessor in stats and boasts a very impressive physical move pool.
Roaring Moon's 139 Attack and 119 Speed makes it the perfect Dragon Dance sweeper. Dragon Dance is mandatory for the Pokémon for it to realize its full potential, and it can easily sweep entire teams after using the move just once. The combination of Throat Chop and Dragon Claw are consistent STAB moves that can be aided by the solid coverage moves available to Roaring Moon.
3 Flutter Mane
Flutter Mane is the Scarlet-exclusive Paradox form of Misdreavus. Its stats are a massive increase over the actual Misdreavus, and the distribution of the Ghost/Fairy powerhouse's stats gives it a great identity as a Special Attacking sweeper.
Since Protosynthesis increases Flutter Mane's highest stat, players get the extreme versatility of choosing between increasing their Special Attack, Special Defense, or Speed. Most players will opt for Special Attack to hit harder or Speed to outspeed opposing Flutter Manes. A devastating 135 Special Attack hits hard and fast, with an easy sweeping potential off the back of two incredible types.
2 Koraidon
The box art legendary Pokémon of Scarlet, the Fighting/Dragon Koraidon initially appears to the player in its odd bike form. However, Koraidon's true form is that of a powerhouse ancient dragon with one of the most overpowered abilities in the game.
Koraidon's ability, Orichalcum Pulse, makes the sunlight harsh and boosts Koraidon's Attack while the weather is sunny. Enabling all Protosynthesis Pokémon and boosting its own Attack is a huge boost, but Koraidon's ability isn't the only thing that makes it stand out. It has great stats across the board, including 135 Attack, and even learns Flare Blitz to take advantage of the Fire move boost from the sun.
1 Miraidon
While many of the best new Paradox forms are the Scarlet exclusives, Violet fans have one thing going for them: The Electric/Dragon Miraidon, one of the most overpowered Pokémon ever released.
Miraidon's stats and 135 Special Attack speak for themselves, but what really makes it so impressive is its ability Hadron Engine. Miraidon boosts its Special Attack in Electric Terrain and summons the Terrain itself. Miraidon's 100 base power move, Electro Drift, is even boosted by the Electric Terrain as well as Miraidon's STAB. Between Electro Drift and Draco Meteor, nothing is safe from Miraidon's outrageous damage output.
Source:gamerant.com