Pokémon Scarlet and Violet has introduced Convergent Species with its reveal of Wiglett, and there a few other monsters who deserve to get this treatment next. This new concept for Pokémon SV's Gen 9 monster designs is very cool, and hopefully more of them will be added sooner rather than later. Scarlet and Violet are currently set to release on November 18, leaving less than a month (at the time of writing) before players will be able to capture Wiglett and any other Covergent Species that come after it.
Pokémon's Convergent Species are alternate forms of returning Pokémon that evolved independently of their inspiration in order to fit similar environmental needs. They're classified as new species with their own names and Pokédex numbers, and their types are radically different from the original form. Convergent Species are a contrast from regional variants, which are a divergent form of a returning Pokémon. Wiglett is the only Convergent Pokémon that's been revealed so far, and is based on Diglett. It is one of the several Pokémon SV leaks to come true after being rumored online for some time.
If the going rumors are to be believed, Pokémon SV will only have one other line of Covergent Pokémon; a mushroom-like Grass-type form of Tentacool and its evolution, Tentacruel. However, as this is still only a rumor, its veracity is questionable, and it's possible that there are more. Even if not, there's still the possibility for Scarlet and Violet to add more Convergent Species in its DLC, or for future generations to use this concept. If and when more Convergent forms come, there are a few Pokémon that deserve to get them more than most.
Pokémon SV Should Add A Toad-Like Convergent Form Of Croagunk
Croagunk is a Poison/Fighting-type Pokémon introduced in Pokémon's Generation 4, the Sinnoh region. It and its evolution, Toxicroak, are both known as the Toxic Mouth Pokémon since they store poisons in the pouches on their cheeks and throats, and are rare Pokémon that can only be caught in the Great Marsh in the Gen 4 games and their remakes. Both deliver their venom through toxic punches, and Toxicroak has sharp claws to aid in this. The Croagunk line is based off of frogs, specifically poison dart frogs, and are an amphibious swamp-dwelling species that presumably uses their poison as a defense mechanism.
If a Convergent form of Croagunk and its evolution were to be made, it has some possibilities. It would presumably reside in a swamp like the original Croagunk, or some form of similar environment. Depending on how far removed from the original it is, a good form for it might be as a toad instead of a frog. A Rock or Ground-type Croagunk that blends into its environment instead of attacking with poison has promise, especially if it was secondary Grass-type to help it disguise itself among foliage. Another design for good type combinations, ones unused aside from two Pokémon each, is as a psychedelic toad with the Ground/Psychic or Rock/Psychic type combination, that uses the sound of its croaking and the sight of it expanding its cheek pouches to hypnotize other Pokémon should its camouflage fail.
The Marill Line Could Make Good Flying-Type Convergent Forms In Pokémon SV
Azurill, Marill, and Azumarill are a three-stage line of Normal/Fairy and Water/Fairy-type Pokémon. Marill and Azumarill were introduced in Gen 2's Johto, and Azurill debuted in Gen 3's Hoenn. Azurill is known as the Polka Dot Pokémon, and Marill and Azumarill are the Aquamouse and Aquarabbit Pokémon respectively, and as such the line is based off of rodents such as mice and rabbits. They use the large balls on the ends of their tails to both hold nutrients and keep themselves afloat in water, but they can also be used for battle. Azurill will also use theirs to bounce around on land.
If Marill's cute mouse-based line of Water-type Pokémon were to get Convergent Species, perhaps the best new design is a line of Flying-types. Azurill, Marill, and Azumarill's Convergent counterparts could develop buoyant tails to stay afloat in the air rather than in water, in which case the balls might be larger, and their bodies might be smaller. If they were to truly fly, then they could be Flying/Fire-types, and use heat or flames for propulsion like hot-air balloons. However, they could also simply use their tails to glide or hover short distances, in which case they could be pure Flying-type or have a secondary different from Fire. Either one could provide a unique design that's distinctive from the Marill line and its type combinations.
Bug-Type Convergent Forms Of The Aggron Line Should Come To Pokémon SV
Aron, Lairon, and Aggron are a three-stage line of Steel/Rock-types that was introduced in Gen 3's Hoenn region. Aggron is one of the few Pokémon capable of Mega Evolution, able to take on a powerful advanced form that's pure Steel-type. All three are known as the Iron Armor Pokémon. They are extremely defensively-focused, with Aggron boasting one of the best base Defense stats in Pokémon. All three members of the line also eat iron, which is used to strengthen their tough metallic armor that they shed between evolutions. Supposedly, Aggron claim entire mountains as their territory, and will defend and maintain them diligently. They appear similar to dinosaurs, and may be based on the Bulgarasi, an invincible Korean monster that devours metal.
If Aggron's line did get a Convergent Species in Pokémon SV, its DLC, or a future generation, perhaps the best design for it would be as a Bug-type. While other types could lend themselves well to a Pokémon with a design similar to the monstrous Aggron's, an insect with a hard, tough carapace has particular potential, especially since the line almost resembles insects already. Beetles in particular could be a good fit for a Convergent Aggron's design, especially the Atlas beetle, which has strong horns like Aggron does. Fighting could be a good secondary type, as could Dark, though several other types could also work well with a Bug-type Aggron. Which Pokémon will get Convergent Species in future games can't be predicted with any degree of certainty at the moment, but hopefully worthy candidates will be chosen, and especially ones that have been largely ignored by Pokémon up until now when it comes to alternate forms and regional gimmicks.