Experimental things you want to see a regional form try and do

Not really any particular ones in mind but things that haven't been done yet.

Since some regionals have additional evolutions the opposite. Lets say a three-stage family becomes a two-stage but in exchange gets an extremely powerful signature move/ability. On topic of regional evolutions a situation in which the line can evolve into a regional variant of the standard final form or branch of into a new evolution. Instead of a single split what about the split happening in the middle stage for example lets use sewaddle instead of sewaddle->swadloon->leavanny it would go regional sewaddle->new coccoon stage->new final stage.

There are some pokemon with very minor form changes like toxtircity or shellos in which the forms become more drastic like different typings, large movepool differences, abilties same could also be added to gender differences to lines which didn't have any. Maybe even for certain lines which are all one gender could have the regional form all being the other gender and the lore is they migrate during mating season.

We've seen various gimmick pokemon so maybe ones which gimmicks are inverted or otherwise altered. Keclon changing it own type could be a regional that instead alters the opponent's type or a version of palafin that has something like "meanie to weenie" in which it starts in a "Fiend" form but becomes normal if forced out