Was already covered in the opening but
How tf did this get past testing lmao, like the contrast between Durant and its effective counterpart Heatmor is only matched, barely, by the Crowned forms of Zacian and Zamazenta. This Pokemon is so strong for absolutely no reason, even without Hustle it has a fantastic Speed tier and a serviceable Attack stat, unreasonably good coverage, and one of the best defensive typings in the game coupled with surprisingly high Defense. Hustle makes it a tad awkward but it's a massive power boost that can be fixed with Hone Claws or an Item.
In its debut gen you get it right before the E4 which is normally kinda gross, but Durant wrecks shop in some of the E4 fights and beypnd so it's not even a bad pick this late in the game. Like seriously if you're running 5 mons + an HM user just get one of these and swap it in after.
Durant would then go on to be a mid-tier menace in Singles to the present day, and even broke out this Gen in VGC due to Dynamax allowing the Hustle boost but ignoring its accuracy drop.
Just when you think it can't get any more ridiculous, the cheeky inclusion of Truant as a Hidden Ability
literally breaks some Battle Facilities as you can Entrainment something and bring in setup users with Protect to run through unopposed. They gave Durant one of the worst Abilities in the game and it got even stronger than before.
Hopefully they do Heatmor some justice like they've been doing in Legends Arceus for a lot of other mons so that these two actually have a real rivalry going on.
Other mons (some already mentioned)
It took getting Drought to fully come into its own but Torkoal is legit. Eruption hits insanely hard provided support, Lava Plume is an excellent move not many things get, has good coverage, and being able to set Sun up has a ton of applications for team structure.
Big Anchor has been in my top 10 since first seeing it. Like why the hell is this thing legal to own. I always think of some novice trainer challenging someone to a Pokemon battle with their cool new starter and the guy sicks an entire fucking haunted shipwreck on them. Beyond aesthetics it's just really fun to use, hits hard, has a lot of good moves, Anchor Shot is better Spirit Shackle, worst things I have to say about it is it should have had less Special Attack for more Defenses and Grass/Ghost is pretty tired at this point, but at least it does the typing well.
This is one good Flying-type move away from being an absolute terror. Tinted Lens is fantastic and should it ever get a move that's like a normal base power with normal accuracy it would be a ferocious breaker. Unfortunately all it has is Air Slash. Also gets Magic Guard somehow because it needed another broken Ability. One of my favorite designs as well, its manages to look like its source material while also showing just how alien the Nazca lines can get in such a hilarious yet horrifying way.
Like yeah it's probably just a stylized bird, but imagine finding out the hard way that this shit's real.
Sorta cheating but by technicality this fits the bill. Base Rotom is cool if lackluster, however the forms are awesome and some have held up super well over time. I will never not dread facing Rotom-Wash unprepared. Shame that they're only allowed one STAB move for their forms and most of them are annoying to use.