You ask for an ETF, not a mutual fund: These ETF's will largely perform the same if you talk about a general "Asia ex China & Russia" vehicle.
If you want something with more individual talent (for over- and underperformance) you have to choose a mutual fund.
So, if only ETF you will have to ask for the specific countries and then select from the wide range of country ETF's.
Potential for a positive surprise (outperformance) in Asia have:
India
Philippines
Vietnam
Nevertheless, forget about G20. That is quite irrelevant performance-wise.
Do not look at Asia through Western glasses. At the end, growth of entire Asia depends more on itself than on the West.
That said, look at bridge countries. The three I mentioned are a good start. You do not need more.