>>14305078India is unlikely because it's a poor shithole, and thus probably a small market for Pokémon games, which to flatter by setting one of the games there would be futile.
Three other settings which are more likely:
Australia. Most of its cities are clustered in the southeast of the country, close enough to form a Pokémon region. There's the outback further inland, and its rich coastal waters with coral reefs and whatnot, all of which would make for memorable environments and unique habitats for plenty of new Pokémon. Tasmania could be the post-game area, hosting a battle zone or whatever.
Another likely location: South-East Asia. It's got a long history, has been subject to the influence of Chinese, Indic, and Islamic culture, and thus sports a variety of unique architectural styles and interesting myths.
It could either be centred on Indochina, in that case probably on Vietnam which offers the most variety, perhaps veering into Cambodia and a corner Thailand.
Or it would focus on the islands, namely Singapore as the obligatory big metropolis, and bordering Sumatra with its varied landscape and many different cultures.
Lastly, I could also imagine Hong Kong. The city is world-famous and sports both Chinese and Western influences. besides the modern, sprawling capital, it's also surrounded by many smaller islands, where one can find cute little villages, some abandoned, shrines to ancestors and Hakka deities. Lots of water routes, then.
