*Updated 3/28/25: Put more thought in items, recommended moves through playthrough(including endgame picks) and added Natures + Tera Types.
I plan on getting Scarlet later this year when Switch 2 launches. That said, here’s a team I came up with.
Meowscarada(Grass/Dark)
Ability: Overgrow
Nature: Adamant
Item: Focus Sash/Expert Belt
Tera Type: Fairy
Moves: Flower Trick, Night Slash, Thunder Punch, Play Rough
All three starters are solid options but I find Meowscarada is a bit better. Doesn’t have the best matchup against the first two Gyms but it more than makes up for that later on in the game, including the first Titan(Rock) and first Star Boss(Dark) that it resists. I opted for Adamant Nature to bump its Attack since its Speed should be more than enough in Story mode. Competitively... you might want to go with Jolly instead. Item use doesn't matter until post-game/competitive, but Focus Sash helps it avoid OHKO. Alternatively, Expert Belt buffs Super Effective hits by 20%. For a Tera Type, I recommend Fairy to turn the tables on Fairy, Fighting, Dark, and notably Bug since Fairy resists the latter three.
For moves, it's a Physical attacker so Leafage is pretty much your primary STAB move until you get Seed Bomb at 17(avoid evolving until then). Replace with its signature Flower Trick when evolving into Meowscarada. It gains Dark Typing at that point and while Bite is the best you'll have, you will get Night Slash at 38. Play Rough is learned at level 47 and simply add Thunder Punch via TM for Gyarados/Pelipper and other Flying Types.
Oricorio(Baile Style; Flying/Fire)
Ability: Dancer
Nature: Modest
Item: Wide Lenses
Tera Type: Ground
Moves: Air Slash/Hurricane, Revelation Dance, Quiver Dance, Roost
Oricorio is available early and the best part of it is that it’s basically 5 types in one since it can change forms. You'll likely first catch it in its Pom-Pom Style or Electric/Flying but it can become Flying/Fire, Flying/Psychic or Flying/Ghost via use of Nectar that you can buy at Delibird Presents. It will perform best under a Modest Nature due to a stronger Special Attack stat and Wide Lenses will ensure its Flying moves hit more frequently. The ideal form for Oricorio though, to me, is the Baile Style(Flying/Fire) since you will want a Fire Type on the roster. For a Tera Type, I find Ground would be useful if needed in a pinch and Oricorio is rather unique with Terastallization due to its signature move.
With respect to its moveset, it starts off strong with Air Cutter at level 13, hence steamrolls Katy and even Brassius. Just be sure to have insurance on that Sudowoodo since it has Sturdy ability and can severely hurt or OHKO you with Rock Throw. It learns Acrobatics at level 23 and despite it being Physical, you're unlikely to have an item for Oricorio at that point in time(so 110 base power + STAB is too good to ignore). It learns Roost at level 30 and recovery is always a nice thing to have. It learns 75 power Air Slash at level 36 and eventually 110 power Hurricane at level 47. You have to choose between more reliable Air Slash that will flinch or the much stronger Hurricane that may confuse the target.
Where Oricorio becomes unique is when it reaches level 40 and learns its signature move Revelation Dance. Revelation Dance is a Special move that takes on the typing of w/e style it happens to be in. If Pom Pom, it's equivalent to Thunderbolt while in Baile Style it's basically a Flamethrower. Pa'u Style yields a move as strong as Psychic and a much stronger Shadow Ball in Sensu Style. The cherry on top to Revelation Dance is that should you Terastellize, Revelation Dance takes on the typing and hence is effectively a stronger Tera Blast but with the caveat that its Special at all times(Tera Blast can use your Attack stat if its higher). The reason I chose Ground for its Tera type is because Special Ground is rather rare and when combined with Quiver Dance is a tough thing to defeat.
The final move in Oricorio's moveset is Quiver Dance. It's an Egg Move and it can learn it via Mirror Herb with another Pokemon with the move at a Picnic. Quiver Dance makes Oricorio a Special monster and if used in tandem with another Oriocorio in doubles basically makes both insanely OP due to its ability Dancer. Dancer copies any Dance move for free so if both use Quiver Dance, you effectively have +2 instead of +1 after 1 turn.
Gallade(Psychic/Fighting)
Ability: Sharpness
Nature: Adamant
Item: Scope Lens or Choice Scarf
Tera Type: Water
Moves: Sacred Sword, Psycho Cut, Night Slash, Aqua Cutter
Gallade was buffed a ton in Gen 9 with Sharpness ability. Sharpness buffs all cutting moves by 50% and its Adamant Nature buffs its Attack that much more. Its item can be either Choice Scarf to outspeed opponents before they can set up hazards/strike first, or Scope Lens to increase Critical Hit chance by 1 stage. Either one works but I would opt for Scope Lens since three of the four moves already start at Stage 2(12.5%). Scope Lens would bring them to Stage 3 or 50%. Critical Hits ignore negative Attack changes, positive Defender changes and all Screens while dealing an additional 50% Damage. Gallade isn't the fastest Pokémon, but this setup should permit it to hit like a truck. For the Tera Type, I opted for Water to yield the team a Water Type in a pinch while also providing STAB to one of its final moves.
For its moveset, your journey is like any typical Ralts with Confusion at 6, Draining Kiss at 12 and Psybeam at 18. Once evolving into Kirlia at 20, your goal should be to get a Dawn Stone ASAP. Upon doing so and evolving into Gallade, it can regain three of the four moves listed. The first one in Sacred Sword is a 90 base power Fighting move that with Sharpness and STAB effectively becomes 202 Power. Sacred Sword also ignores changes to Defender stats(ex: Defense/Evasion). Next is Night Slash, a Dark Type coverage move that with Sharpness is 105 Power with increased Crit chance. Finally Aqua Cutter is a new Gen 9 Water Type move that is 105 Power thanks to Sharpness and will Crit more often just like Night Slash. To round out its moveset, you'll have to journey to level 42 to grab its Psychic STAB move of Psycho Cut. Psycho Cut, thanks to Sharpness is 105 Power and will Crit more often.
Tinkaton(Fairy/Steel)
Ability: Mold Breaker
Nature: Adamant
Item: Wide Lenses or Muscle Band
Tera Type: Steel
Moves: Play Rough, Gigaton Hammer, Bulldoze, Tera Blast
Tinkaton has a great typing combined with a great ability. Fairy/Steel is arguably the best typing in the game while Mold Breaker is a really powerful ability if you can take advantage of it. It's speed is adequate so I opted for Adamant Nature to maximize its Attack. Wide Lenses ensures one of its moves hits more reliably or you can roll with Muscle Band to gain another 10% for this Physical whack-a-mole. For Tera Type, I can't think of anything better than Steel to maximize its signature move.
For its moveset, you'll be primarily a Steel type as a Tinkatink with Metal Claw(level 8) and the Normal type move Covet at level 11. Draining Kiss is learned at level 17 but anything stronger on the Fairy side will be a long wait since you won't learn the Physical Fairy move Play Rough until level 35 as Tinkatuff. Upon evolving into Tinkaton at level 38, you'll learn its signature Steel move in Gigaton Hammer. Has massive 160 Base Power but cannot be used the following turn. While in cooldown, you can use the Normal Type move Tera Blast that changes to Steel typing when Terastallized. To round out the moveset, I recommend Bulldoze to take advantage of its Mold Breaker ability against Levitate users. Sadly, both Tinkatink and Tinkatuff cannot learn Bulldoze so you must go into the battle against Iono without it. However, on the rematch, that Mismagius is fair game.
Garchomp(Dragon/Ground)
Ability: Sand Veil
Nature: Jolly
Item: Leftovers
Tera Type: Steel
Moves: Dragon Claw, Earthquake, Iron Head, Swords Dance
Garchomp is the best Ground type bar none for any playthrough. It's Ability Sand Veil will largely go unused but its Nature in Jolly will make it an even greater threat by boosting its Speed. I opted for Leftovers on Garchomp since the longer this monster is alive, the more pain it will inflict on the enemy. For Tera Type, its a very easy choice in Steel since its biggest vulnerabilities both happen to be weak to it while also resisting Dragon too.
For moveset, Garchomp largely starts out as a Ground type with Bulldoze at level 18 being more than adequate until you can teach it Earthquake via TM. For Dragon STAB, you're relegated to using Dragon Breath until you learn Dragon Claw at level 42 as a Gabite(36 as a Gible but who would do that to themselves). To round out the moveset, you'll want to teach Iron Head to counter Ice + Fairy types that gains STAB when Terastallizing and Swords Dance so that it can buff itself into a Physical monster.
Gengar(Ghost/Poison)
Ability: Cursed Body
Nature: Timid
Item: Choice Specs
Tera Type: Electric
Moves: Shadow Ball, Sludge Bomb, Dazzling Gleam, Thunderbolt
Gengar is a Pokémon I have not used(surprising given I have Gen 1 Yellow). Given that we aren't being trolled by an in-game Trade this time around, Gengar is a very fast Special Attacker. A Timid Nature will boost its Speed a bit more while Choice Specs will lock you to one move but buff its Damage by 50%. For its Tera Type, I opted for Electric given its Speed and Special Attack remind me a lot of Jolteon(albeit with Offense/Speed reversed). The only thing that would make Tera Electric better is if it still had its Levitate ability... cries. Got to give Iono credit for using it.
As for Moveset, that depends largely on what level you obtain Gengar at. It learns Hex at level 24 but doesn't learn Shadow Ball until level 48 so I advise teaching it via TM earlier if it can be helped for the Gym Battle with Ryme. For its Poison STAB, that will have to be taught via TM and you have two choices. Sludge Wave is a tad stronger but hits everyone on the field, including Allies, or Sludge Bomb to limit the damage to just one Pokémon. Of the two, I prefer the latter since it has a 30% chance to Poison as well. I then recommend Dazzling Gleam via TM to cover its Dark Type weakness and Thunderbolt to deal with Flying Types since the team technically doesn't have one and gains STAB if you Terastallize.
