Not really.

Any game where your game-world movements don't match your real-world movements is what causes motion sickness.

It's as simple as that. If you're sitting in a mech, once the mech moves, you're likely to get sick, because you're moving in the game world, but not the real world.

There are ways to kind of fool your brain to make it work, but it's not 100%. For example, in Gorn, one of the movement options is to move an arm forward, then pull it back while holding the trigger, kind of like you're pulling the world. But if you alternate arms as you do it, your arms kind of simulate the swinging motion of walking, and that can be enough to drastically reduce or even eliminate the sickness.