I haven’t heard a lot of complaints of motion sickness, but it’s a possibility. My son in law has motion sickness and didn’t have any issues with it, but that doesn’t mean you won’t.
After you finish one game, the ride car spins quickly around as it moves to the next game. Some people find the spin jarring. You can tell it’s coming, so can brace.
You might want to check out videos of this one on YouTube. A YouTube poster named Big Fat Panda does really good videos in general from the standpoint of showing guests with disabilities what to expect.
This ride is part of the new Toy Story Land, but other than the entrance and exit, it should be pretty much the same.
There is a thread near the top of this board that has information about the Pandora attractions. The first few pages are gathering information before and right after Pandora opened.
Flights of Passage is really variable with reports of motion sickness. Some people have issues, some people had no problem if they looked away at certain points and some people had no problems because the motion you feel really seems to match the motion you see.
Na’vi River Journey is a very smooth and gentle boat ride.