I’m not advocating to use them in a ranked setting as those should definitely be “only what you get this generation”. But if I’m having a fun battle with my friends then I should be able to spam them with a Toxapex using Scald. There is no reason why someone who enjoyed the older games and transferred things throughout the years should not be able to enjoy those benefits.
The problem lies in how the game is going to tell them apart. It can't read your mind on what you intend to do with those Pokémon. The other alternative is to allow only Pokémon that you've caught within that generation to battle in Ranked and in Online Competitions, which is less fair.
Transfer-only moves give players who have stuck with the series the same advantages as transfer-only Pokémon, if not less. And while I agree that this might be regarded as unfair I also feel like there isn't anything wrong with rewarding players for sticking with the series for a long time (as far as having to trade for something can be considered unfair). Banning moves that you cannot obtain within a game from competitive formats while still letting you use them in single-player would probably have been my preferred approach.
I also feel like it is worth pointing out that there are still plenty of time-sensitive elements in the games. A lot of the Switch games gave you event legendaries only if you had save files from previous games on the Switch. The same can be said for things like Tera Raids, if you miss out on a timed event with an exclusive move or Pokémon before you bought the game you will be at a disadvantage.
That was how
Sword and Shield did it: it allowed your moves in, with an NPC resetting the moves and giving the Pokémon a little icon indicating it's eligible for competitive play. I see no reason why
Scarlet and Violet couldn't work the same way; it should be pretty easy to update the game to have an NPC that does the same thing.
That being said, I have been playing since Generation I, and I would say that I don't want to have any edge over the people who only started playing with
Scarlet and Violet. I'm not against rewarding longtime fans, but I'd hope they'll be ones that don't give any sort of practical advantage, like shiny Pokémon or something.
The save file bonus Pokémon in Generation VIII are all Mythical Pokémon (I can recall Mew, Celebi, Jirachi, Shaymin, and Darkrai), none of whom were available to use in
Sword and Shield's Ranked except in its very last season (which began 2 months prior to
Scarlet and Violet's release and was basically them going "We're done--do whatever you want, bring whatever you want, we don't care anymore") and in one single Online Competition, "Battle of Legends," which had only a participation award and also allowed all Legendary Pokémon in. And of those, I think only Mew was actually allowed at all. So far, all of the Pokémon exclusive to Tera Raid Battles are also banned in Ranked (and neither is Hisuian Zoroark). That being said, all of them are also breedable, and them being starters, turn up pretty often in Surprise Trades (particularly the most popular ones in Charmander, Scorbunny, and Froakie).
