Actually Let's Go had many exclusive level-up moves, like Quick Attack Seaking, Razor Leaf Farfetch'd, Minimize Wigglytuff, Moonblast Muk, and Sucker Punch Victreebel(though the latter was also available as a Gen IV exclusive Tutor move, it was now legal with Power Whip). Granted, a lot of those moves(but none I listed) were a case of either adding Egg moves to their level-up pool due to there being no breeding in the game, or more often they just wanted every single Gen I move to be usable in the game, so they made sure there was at least one Pokemon that could learn each one, since many had been exclusive to Gen I Pokemon via old TMs/HMs/Tutors, with most, if any, natural learners of the move being from later gens(like Razor Wind)
You know what, I’ll fully own up to being wrong there. I played maybe 4 hours of LGPE and stopped after getting to the go park so I could import shinies and meltan. I was looking mostly at the TMs since they were the familiar part from Gen 1 but I totally forgot about wacky moveset changes like moonblast Muk.RIP LGPE Ice Shart Sandslash-A. :/
I still stand with my stance of a lot of these moveset changes sticking, though. Maybe it’s just wishful thinking, but a lot of these changes are answers to problems a lot of these Pokémon have had for a decent while. Someone at Gamefreak for sure notices little holes in movepools and slowly patches them over with stuff like Extremespeed Linoone, Meteor smash Lucario, and even giving Melmetal back Earthquake in IoA. It’s rocky evidence, but giving something like Empoleon Roost is such a boon compared to all the LGPE changes (aside from the already available Teleport Slowpoke I guess?) I can’t imagine them rolling it back if Roost is still a TM or tutor in Gen 9.
On the unrelated of BP and accuracy changes, both LGPE and PLA’s movesets feel warped for the sake of the experience. I think all of PLA’s buffs and nerfs to long standing attacks will be rolled back like the LGPE move changes (sans teleport ofc). I also expect moves that are effective clones of existing attacks like that new fire type outrage and the water type double edge will gain their main series’ clones accuracy and BP.