User blog comment:FairyRaven/Fairy Tail Chapter 429 & 430: Code Blue & Purification Ritual, Review and Commentary/@comment-109.66.34.228-20150420110342/@comment-7418318-20150421081816

In the manga we only ever see Natsu getting sick in vehicles, other artificial moving things (i.e. Nirvana, which I can't bring myself to call a vehicle) and slides.

On living beings he never had trouble, which includes Coco's Legion Legy-pyon.

I know in the anime in the KotSS arc he initially got sick on that giant flying Octopus of Byro, but even there he no longer got sick on him once Zentopia and FT banded together and thus the Octo became a comrade. But either way it was a filler arc so whatever.