With Empoleon gaining Competitive after all these years, Ribombee's fast and hard hitting Special Attacks, and Gliscor's great Attack, great Speed, and great Defense, there are many Pokemon reintroduced in the Teal Mask DLC that can be good in competitive.
First of all, let's start with Empoleon..after almost 20 years of sitting with Defiant, it gained the new ability Competitive. With a pretty good typing and some nice stats and decent bulk, you can make use of this Pokemon. Here is a moveset you could try:
Empoleon (M) @ Leftovers / Life Orb
Ability: Competitive
Tera: Grass / Flying
EVs: 252 Def / 200 SpA / 52 SpD
Nature: Modest
- Hydro Pump
- Flash Cannon
- Ice Beam
- Tera Blast (Grass/Flying)
Note: Empoleon can only be obtained in SV if you have Pokemon HOME and transfer it.
Next is Ribombee, with it having great Special Attack and Speed, and being able to get Sticky Web, you can really slow down your opponents team. You could try a moveset like this:
Ribombee (F) @ Life Orb
Ability: Shield Dust
Tera: Ground
EVs: 252 SpA / 252 Spe / 4 HP
Nature: Timid
- Tera Blast (Ground) / Dazzling Gleam
- Bug Buzz
- Draining Kiss
- Quiver Dance / Sticky Web
Then there is Gliscor, he has decent Atk and Spe while having great Def. He also has a typing with only two weaknesses, x2 to Water and x4 to Ice. You could try a moveset like this:
Gliscor (M) @ Life Orb / Expert Belt / Toxic Orb
Ability: Poison Heal / Hyper Cutter
Tera: Steel
EVs: 252 Atk / 100 Def / 156 Spe OR 252 Atk / 252 Spe / 4 Def
Nature: Adamant
- Swords Dance
- Earthquake
- Tera Blast (Steel) / Poison Jab
- Toxic Spikes
Another Sinnoh starter that got a buff is Torterra, with it having great HP, Atk, and Def you can make this think put some use because it got SHELL SMASH! You could try a moveset like this:
Torterra (M) @ Leftovers / White Herb
Ability: Shell Armor
Tera: Rock
EVs: 252 HP / 252 Atk / 4 Def
Nature: Adamant
- Earthquake
- Shell Smash / Iron Defense
- Iron Head
- Body Press / Tera Blast (Rock)
And the final Pokemon I will cover is Alolan Ninetales. With Ninetales being reintroduced in the DLC, It's Alolan form comes along. With Snow Warning and good Spe and Spd, you can make good use of this Pokemon. You can try a moveset like this:
Ninetales-Alola (F) @ Leftovers
Ability: Snow Warning
Tera: Water
EVs: 252 Spe / 128 SpD / 128 SpA
Nature: Timid / Modest
- Ice Beam
- Moonblast
- Auroua Veil
- Tera Blast (Water)
Note: Alolan Ninetales can only be obtained in SV if you have Pokemon HOME and transfer it.
There is some Pokemon that I did not mention on this list because 1) It would be such a long answer and 2) because I can't list every Pokemon that is good (from the DLC) in one answer.
Hope I helped!