>>19467631>>19467441>>19467534For the deep-sea effect I'd make it an aquarium with several floors.
First floor could be just jungle with some streams but no trainers, a bit of a bluff as one might expect this to be the grass gym. Or skip this and go right to the next floor.
The floor under that is a mangrove type vivarium where the trainer(s) favor(s) near land water pokemon like Bullotus, Chlorofin, Hydranticus and Lutrajet.
Then it's actual under water with the usual under water suspects Nurshary, Oarwish, Mawasite.
Then the final floor is deep sea based. Glowing jellyfish maybe. The pokemon used here are Jawgodon, Glocto and Dunkywunkr.
To get from one floor to the next you'd have to solve puzzles.
(For the pokemon examples I didn't take level into account and just took the final form)
