Meanwhile, in Pixelmon, the old moves are all the same and the battle mechanics are unchanged. It wouldn't make sense to add the new Legends Arceus moves as they are, since they were designed for an all-different battle system where the moves are all changed. And implementing that system (frostbite status, drowsy status, strong style, agile style, move fixation, etc) would be a lot more complicated than just adding the moves as they're listed below.
As for concerns over whether or not these mechanics should be changed for Pixelmon, there's a precedent here, since Hisuian Qwilfish doesn't evolve by water stone in the real games either.
In summary, I think these moves should be changed in the interest of balance and fun.
(credit to Legends Alliance for coming up with these move changes, Discord link in link below)
https://docs.google.com/spreadsheets/d/1TPrLq6zdmAek5Qb71y6gDI-_TLUehf54ncwIvxfovtk/edit#gid=0