Generation 9 introduced 107 new Pokemon in Pokemon Scarlet & Violet. Despite this, there are still many Pokemon from past generations that appear in Paldea. It's highly likely there are going to be Paldean Pokemon in the next mainline Pokemon game for Generation 10. With over 100 to choose from, there's no telling how many Gen 9 Pokemon will appear in the Gen 10 games.
While it's likely that the Paldean starters and box-Legendaries of Pokemon Scarlet &Violet will return to Gen 10, the rest of Gen 9 won't be as fortunate. Previous generations of Pokemon will have to compete with other generations and the newcomers for a spot in Generation 10's region. Some Pokemon are more likely to appear than others because of their popularity and their battle prowess.
10 Charcadet, Ceruledge, & Armarouge
Charcadet and its evolutions are Fire-type Pokemon, but Armarouge (Scarlet) is a Fire/Psychic-type while Ceruledge (Violet) is a Fire/Ghost-type. Charcadet can be caught in both Scarlet and Violet. To evolve it into Armarouge, trainers need to give it Auspicious Armor. To evolve it into Ceruledge, Charcadet needs Malicious Armor.
While the evolution items are version-exclusive, it's very likely that they'll be merged into one game by the 10th generation, much like the Sweet Apple and Tart Apple from Sword & Shield were in Gen 9. Armarouge and Ceruledge's unique typings make them extremely versatile in battle.
9 Nacli, Naclstack, & Garganacl
Nacli and its evolutions are Rock-type Pokemon with a unique Ability: Purifying Salt. This Ability prevents status conditions while also halving damage received from Ghost-type moves. Garganacl has made a name for itself in Raid Battles.
In battle, its high Defense and solid Special Defense make it an excellent wall, and its high Attack means it can hold its own against foes. If Gen 10 brings back a mechanic similar to Tera Raids, then the Nacli-line would be a perfect candidate for battle.
8 Tinkatink, Tinkatuff, & Tinkaton
The Tinkatink-line is an all-female species with the Fairy/Steel-typing. Amusingly enough, the final evolution, Tinkaton, is one of Corviknight's predators. Basically, they're the reason why Flying Taxis are carried by Squawkabillys in Paldea.
While Tinkaton and its pre-evolved forms may be outdone by other Fairy or Steel-type Pokemon, a survey has revealed that Tinkaton is the leading Gen 9 Pokemon in a popularity poll, even beating out the Starter Pokemon. There's a solid chance the Tinkatink-family will return for Gen 10. If their Dex Entries are anything to go by, they'll have no problems adapting to a new environment.
7 Shroodle & Grafaiai
Grafaiai was teased in a trailer for Scarlet & Violet before the games' worldwide release. Some fans initially thought it was supposed to be Paldean Smeargle, but this quickly turned out to not be the case. Grafaiai and its pre-evolved form, Shroodle, are both Poison-type Pokemon, unlike the Normal-type Smeargle. Furthermore, they can't learn Sketch and have a full learnset and can even learn moves via TMs.
Poison-types have received a new type advantage in Fairy-typing, meaning they're a bit more popular than they used to be pre-Gen 6. While Grafaiai has to compete with other Poison-types like Salazzle, its high Speed and Attack make it excellent for taking on gym battles well into the end-game. Should these two Pokemon return for Gen 10, they'll be perfect for battling the new Fairy-type and Grass-type Pokemon.
6 Cetoddle & Cetitan
According to its dex entry, Cetoddle and Cetitan are thought to be related to Wailmer. Despite this, they're Ice-type Pokemon, and the only Water-type moves they'll learn are through TMs. Cetoddle itself seems to have quite a reputation in the Pokemon fanbase due to its adorable looks. Like Tinkaton, the high chances of this family returning for Gen 10 will more than likely be thanks to its popularity and less so its battle prowess.
The Cetoddle-line aren't weak Pokemon by any means though. As Cetitan, they have very high HP and Attack, but their Defense and Special Defense make them a weaker wall compared to Rock-type Garganacl. Should these two Pokemon return, hopefully, it'll be alongside their Wailmer relatives.
5 Greavard & Houndstone
There are many new dog Pokemon in Scarlet & Violet. Fidough appeared in a gameplay trailer and was a hit with fans, while Mabosstiff, the evolved form of Maschiff, has significant story relevance thanks to Arven. Then there's Greavard, who made an appearance in a teaser trailer similar to Grafaiai. Like Fidough, it was received quite well due to its personality and looks.
When Scarlet & Violet neared launch, Greavard was revealed to have an evolution: Houndstone. While not as popular as its pre-evolved form, it has great Defense, Special Defense, and Attack stats, meaning it can take a hard hit from an opponent. Pokemon has many Ghost-types, including the fan-favorite Mimikyu, but the Greavard-line would be nice to see in among a new generation of Pokemon simply because of the affectionate personality it exhibits towards its trainer.
4 Flamigo
As far as Pokemon designs go, Flamigo is considered underwhelming by many fans. It's a Flying/Fighting-type, making it weak to Psychic, Fairy, and Flying-type moves, which regular Flying-type don't normally have. However, Flamigo has an impressive base stat total of 500, with high Attack and Speed. It also learns the Dark-type move Throat Chop, which is a great counter against Psychic-type Pokemon.
Pokemon with the Ghost-typing are immune to Normal and Fighting-type moves, but Flamigo averts this with its Ability, Scrappy. This allows Normal and Fighting-type moves to hit Ghost-type Pokemon. While Flamigo could be helpful in the first few areas of Gen 10, it's very likely it'll be replaced as players reach higher-leveled areas.
3 Flittle & Espathra
Flittle is a weak Pokemon that evolves into the speedy, Special Attacker, Espathra. These are both Psychic-type Pokemon, but once Flittle evolves, it will learn its signature move: Lumina Crash. This has 100% Accuracy and deals 80 damage, but it will also lower its target's Special Defense by two stages.
Espathra outspeeding most Pokemon means it's likely to strike first, allowing trainers to easily sweep enemy teams. While Espathra may be overshadowed by other Psychic-types and newcomers in Gen 10, it can be a difficult Pokemon to battle against for unsuspecting trainers. Those looking for a challenge may want to see the return of the ostrich Pokemon in the next mainline installment.
2 Koraidon & Miraidon
Throughout Scarlet & Violet players' journey, they'll have Koraidon or Miraidon by their side. Unlike previous box Legendary Pokemon, Koraidon and Miraidon form a strong bond with the player character before they're officially caught. They even get their own character arc in The Way Home storyline. While it seems Miraidon is the preferred Legendary in the fanbase, that shouldn't stop them both from making a return in Gen 10. Past games such as Sword & Shield included Legendary Pokemon from Gens 1-7, so there's no reason why these Paradox Pokemon can't come back for a new generation.
Miraidon has a unique Typing and is a great Special Attacker, while Koraidon makes quick work of difficult Tera Raids. Given the closeness some players may have formed with Koraidon and Miraidon, there's no doubt they'll be welcomed back with open arms in the next installment. Of course, it's unlikely they'll be operating as the player character's bike in Gen 10.
1 Sprigatito, Fuecoco, & Quaxly
Just like the Legendary Pokemon, the Starter Pokemon for each generation usually appear in the next mainline game; either as a post-game reward or exclusive to online raids. Sprigatito seemed to have won fans over when the Starter Pokemon were first revealed, but all three Gen 9 starters have great final evolutions.
Meowscarada is a quick Physical Attacker that learns the exclusive move, Flower Trick. Skeledirge is a slower Pokemon, but its signature move, Torch Song, increases its already-impressive Special Attack by one stage in battle. Finally, Quaquaval is a great all-arounder whose Aqua Step move increases its Speed. Each of the starters works great in gym battles and even Tera Raids if they have the right moveset. With Meowscarada and Fuecoco placing high up on the Japanese survey, these three will almost certainly be added to Gen 10 somewhere down the line.
Pokemon Scarlet & Violet are available now for the Nintendo Switch.