As far as new Pokemon go, I'm hoping for a number similar to the 4th gen. We got a number of NEW Pokemon, a hoard of new evolutions for older Pokemon, AND a ton of legendaries and mythical Pokemon.
If the speculation if correct about Hawaii being the region's real-world inspiration, then I'm guessing for a lot of new grass, bug, water, and rock types. Maybe add in a few poison and fire types (volcanoes, of course) as well.
The inclusion of a dolphin Pokemon, a new bird and butterfly, and I would personally love to see them create a Peacock-themed Pokemon. Animals that are traditionally found in tropical regions; geckos, amphibians, insects, small rodents, monkeys, etc.
I always tend to pick out at LEAST six favorites, including ONE starter, so my teams for each generation tend to include ONLY Pokemon FROM that generation. I hope that I'm able to accomplish this once more!