There isn't much water in this region, so pokemon here have to be able to survive outside of the water
https://bulbapedia.bulbagarden.net/wiki/Water_(type)I'm thinking something along the lines of usual garbage shitmons like psyduck, poliwag, ect, but also let the player catch clamperl and give the player a choice of one of the two deep sea items, like in gen 3. Mudkip, Wooper and Shellos are also good ground/water options, but you obviously don't need all 3. Alomola, Clauncher and Wishiwashi could fill in the blanks
There are no sea routes in Orre, so if the game made use of one, it would be a good excuse to give the player a tentacool, cloyster, chinchou and carvanha. Around oasis like areas, lotad and surskit could be found, and you can encouter wingull anywhere close to the sea, nothing ground breaking here. Binacle and Mareanie could be found in the beach like areas
