You cannot do so any more. That feature was only included for updates where the protagonists received redesigns. As in v12 none of the protags received redesigns, the appearance changer NPC from v11 was removed.
my point is as someone who as played rejuv for a long time is that you should be surprised when a non-shadow pokemon gets weird moves (such as the Steam Eruption Decidueye mentioned). You should recognize it as not the norm in cases such as this.
SwSh comes out in less than 3 months. The normal dev time for a release of rejuv is around a year. The release time between v11 and v12 was incredibly short and should not be taken as the norm.
Something to remember: the dev time of v12 was an incredibly short amount of time compared to previous versions, so expecting v13 within the same amount of time when they also have to add in an entire new gen is not the smartest train of thought.
Pokemon Reborn (and Rejuvenation) both use the Generation 7 movepools for Pokemon. You seem to be looking at the Lets Go movepools, which are drastically different from the main games.
One move is why, and that move is Eruption. Not only is it boosted on a number of fields that make it super powerful, it also transforms other fields. Not to mention it is also a spread move that does massive damage.
They aren't being supported anymore because the protags all got new sprites that the dev team likes more (more polished etc) is the best reason i know.
And nah, I much prefer the actual sprites.
What does that mean.
So you didn't have any mods installed before the update, but you installed mods for v12 before actually opening your file in v12 without mods? did I get that right?
its Kings Rock so each hit has a chance to flinch. so its a pretty high flinch chance (not 100% tho). If you have nothing else that can deal with it (outside the flinches it isnt super strong or anything), pick up a Steadfast mon.