Guardians is kind of an unusual ride in terms of people's reaction to it. Some people who normally get motion sickness didn't when riding it and others who never have before, did. In most discussions I've seen, about 1/3 of people get mildly to severely motion sick. I was one of the people who didn't expect motion sickness, but I felt very sick. This was something I wrote soon after it opened:
Some people who never/seldom have issues with motion sickness are having problems with this ride and some who have problems with lots of rides aren’t having problems. Some have also found their usual medication for motion sickness isn’t working on this and others report it working better than usual.
I think the biggest variable might be what kind of motion causes issues for people on other rides and to what extent/how it is present or combined on this.
For some people, it’s screens. For others, it’s the up and down of roller coasters, the drops or how smooth the motion is. For some it’s spinning, especially being turned in a direction that doesn’t match the direction the vehicle is going. For some, it’s banking or turns. Or how long the ‘problem’ motion lasts.
This is a fast, but smooth roller coaster with pretty much constant banking. It has a backwards launch, which wasn’t a problem for me, but might be an issue/disorienting for some.
It’s pretty much constant banking turn going right into another banking turn. Many of the turns are pretty tight and there are no lifts or slower spots to give a breather between banking. There are screens everywhere you look and the ride car uses ‘Omni-motion’ like Haunted Mansion to point your ride car toward the screen/area you are supposed to look like. Where you are pointed is often not the same direction as the vehicle is traveling.
The difference compared to Haunted Mansion is the speed of motion - it’s one thing to have your doom buggy sideways compared to the track while going slow. It’s very different to do the same thing on a fast, banked turn.
Guests who don’t have issues with those specific elements might not have issues.
And some who haven’t had issues with the elements separately or slowly might have issues with the combination.