I checked Klinklang, one of my favourite 'mons despite ... umm ... everything. With a new generation, surely it would get a few new tricks up its sleeves(?!?), right?
Oh, look, it gets Power Gem now! And ... it's otherwise completely unchanged. Or, wait, Gear Grind (its best STAB by far) is moved from level 16 to level 32.
And it still rides the train of Plus/Minus even as all the other passengers have got off. The Klink line and Toxtricity are the sole users of Plus, while the Klink line and the Electrike line (HA only) are the sole Minus users. That's right, the Klink line still got both those (functionally identical) abilities, apparently for the purpose of boosting Klinklang's base 70 SpA to become a special attacker (hence the addition of Power Gem to a movepool that currently only has Steel, Electric and Normal-type moves in it). In any other circumstances, its base 100 Attack is a much more powerful stat, but it only learns Steel and Normal-type physical moves, plus Wild Charge. Oh, and Return is no more, so it'll have to rely on Facade for Normal-type coverage.
So the Klink line is still as useless as ever; arguably even more than before since its best move has been shifted from the early-game to mid-late-game. Klang still evolves at level 49. Maybe it could be situationally useful alongside Toxtricity if the game has plenty of Double battles, but I'm not really holding my breath on that front.
...so yeah, I'm not using Klink in SwSh. I used it when I last ran through USUM, that'll be enough for a while.