Can you move to a different country if you are in the reserves?

If you live in Germany, Japan, or Korea there are Reserve opportunities there.

Better read close tho- normal service time is 8yrs, not 4. In your case I assume 2 years active, then enlisted 2 yrs USAR. with the other 4 in the IRR

I'm assuming you completed your 2 years active. If so, the answer is probably yes you can live in a different country. I'm basing my answer in my long-time-ago experience flying transport aircraft. We picked up Space-Available reservists in CONUS and Overseas who were traveling to their drill sites. It makes a very long weekend when you have to travel from somewhere like the UK to your drill location in CONUS and back. Better choice would be to become an IMA (don't know if there's IMA slots for junior enlisted) and drill with an overseas unit closer to the location where you live. I remember giving a lift to an Army Reserve Major IMA who lived in Greece and drilled with a unit in Germany. He made a monthly trip from Athens to Rhein-Main and back. The C-130 scheduled shuttles made this possible in the 1970s. All the passenger terminal folks knew him well. He worked in the family business in Greece, so he could take a week off to go to drill. Your circumstances will be different most likely. Look into all the options for travel and basing before you decide.

I have to imagine it would get pretty expensive flying to drill each month...

In order to fulfill your contract you have to attend training in the Reserves - there are no reserve locations in China. You could (out-of-pocket) fly to training each month or agreed upon dates. After your contract is up, it won't matter where you live.
You should not be eligible for the IRR option until you have fulfilled your initial obligation.
As to moving to another country, since you gave up citizenship you would have to have some sort of work visa to be allowed to stay past the 90 day visitor stay.
Review your contract and if needed talk to a retention NCO - they can look up unit vacancies/MOS slots and give you your best option for your reserve requirements.

The answer you seek has many variables. It depends on the type of Reserve position you will hold. Traditional Reservist - meaning you drill once a month with a Reserve unit. IMA - a Reservist assigned to a active duty unit, you commit to 30 days a year. Or the IRR - you don’t drill at all. You are pretty much a name on a piece of paper.

I don’t see how you can meet your Reserve duties in a Traditional Unit if you live in another country. IRR - would be your best chance of meeting your commitment while living overseas.

You need to discuss it with your servicing JAG. There might be some contractual issues, but more serious security issues.