Yo guys, I have possible more proof that it is indeed Hawaii. At least parts of it. I am thinking that it will be taking areas from every big island that is well known.
I bring this up because, if you finish the Hoenn Pokedex, Treecko, Mudkip, and Torchic have flowers. These flowers remind me of lais. Which again, goes to Hawaii.
Mudkip is wearing it on its head. Treecko seems to be making one, and Torchic is wearing it around its head. Not only that, but the flowers in which they are using, look exactly like the floweres they use in Hawaii. The colors used are Red and Yellow, this could stand for the Big Island Hawaii and Oahu, which is one of the smaller islands. These islands use red and yellow as their colors.
I don't think it will be islands though, unless it is split it to a few islands, each island centered around one tropical culture. I just don't see us having an Archipelago as a main region. I could see there being 3 large islands, each connected by a bridge or something. Each Island would be centered around 1 or 2 tropical cultures.
Sorry if any of the above has already been said by someone.